Sacar formulario fuera de función php

Hola:

Tengo un plugin para wordpress que mediante shortcode muestra un formulario para calcular tiempos de carrera, la cosa es que no funciona en unas webs pero en otras si.

Aquí no funciona https://de-senderismo.net/blog/calculadora-de-tiempos/ Aquí si funciona https://zapatillas-trekking.com/pruebas/

¿Cómo puedo poner el formulario fuera de la función? El código del formulario es este:

	{
		$calculator = '<form method="POST">
	<table cellspacing="0" cellpadding="4"  cellspacing=1 border="0" align="center" width="420">
	<!--Title Rows-->
		<tr><td bgcolor="'.$this->option('time_hd_color').'" valign="top" align="center" colspan="2" ><FONT color="'.$this->option('time_hd_text_color').'"><B style ="color:'.$this->option('time_hd_text_color').'" >TIEMPO<span style="font-weight: normal; display: block;">Para Calcular tu Tiempo, Rellena tu Distancia y tu Ritmo, Luego Pulsa el Botón</span></B></FONT></td></tr>
		<tr class= "time-bg" style="background-image: url('.$this->option('time_bg').') !important; background-size: cover;     background-position: center;" bgcolor="'.$this->option('time_bd_color').'">
			<TD class="body-td" valign="top" align="center" style="padding: 20px; ">
				<table>
				<tr>
					<td class="smallText" align="center">HORAS</td>
					<td class="smallText" align="center">MINUTOS</td>
					<td class="smallText" align="center">SEGUNDOS</td>
				</tr>
				<tr>
					<td align="center"><input type="text" name="thr" size="2" maxlength="2"></td>
					<td align="center"><input type="text" name="tmin" size="2" maxlength="2"></td>
					<td align="center"><input type="text" name="tsec" size="5" maxlength="6"></td>
				</tr>
				</table>
			</td>
			<td style="padding: 20px; " class="body-td" align="center" valign="top">Pulsa Aquí:<BR><INPUT type="button" class="pulldown" onClick="var myform = document.forms[0]; CalcTime(myform)" value="CALCULAR TIEMPO">
			</td>
		</tr>
		<tr><td bgcolor="'.$this->option('distance_hd_color').'" valign="top" align="center" colspan="2" ><FONT color="#FFFFFF"><B style ="color:'.$this->option('distance_hd_text_color').'">DISTANCIA<span style="font-weight: normal; display: block;">Para Calcular tu Distancia, Rellena tu Tiempo y tu Ritmo, Luego Pulsa el Botón</span></B></FONT></td></tr>
		<tr style="background-image: url( '.$this->option('distance_bg').') !important; background-size: cover;     background-position: center;" class= "distance-bg" bgcolor="'.$this->option('distance_bd_color').'">
			<TD style="padding: 20px; " class="body-td" valign="top" align="center">
				<input type="text" name="dist" size="7" maxlength="8"> <select name="dunit" class="pulldown">
					<option value="Mile">Millas</option>
					<option value="Kilometer" selected>Kilómetros</option>
					<option value="Meter">Metros</option>
					<option value="Yard">Yardas</option>
				</select><BR>
				O<BR>
				<select name="event" onChange="setDunit(document.forms[0])" class="pulldown">
					<option value="special">Selecciona Distancia</option>
					<option value="Marathon">Maratón</option>
					<option value="Half-Marathon">Media Maratón</option>
					<option value="5K">5K</option>
					<option value="5M">5M</option>
					<option value="8K">8K</option>
					<option value="10K">10K</option>
					<option value="15K">15K</option>
					<option value="10M">10M</option>
					<option value="20K">20K</option>
					<option value="15M">15M</option>
					<option value="25K">25K</option>
					<option value="30K">30K</option>
					<option value="20M">20M</option>
				</select>
			</td>
			<td style="padding: 20px; " class="body-td" align="center" valign="top">Pulsa Aquí:<BR><INPUT type="button" class="pulldown" onClick="var myform = document.forms[0]; CalcDist(myform)" value="CALCULAR DISTANCIA">
			</td>
		</tr>
		<tr><td bgcolor="'.$this->option('pace_hd_color').'" valign="top" align="center" colspan="2" ><FONT color="#FFFFFF"><B style ="color:'.$this->option('pace_hd_text_color').'">RITMO<span style="font-weight: normal; display: block;">Para Calcular tu Ritmo, Rellena tu Tiempo y tu Distancia, Luego Pulsa el Botón</span></B></FONT></td></tr>
		<tr style="background-image: url('.$this->option('pace_bg').') !important; background-size: cover;     background-position: center;" class= "pace-bg" bgcolor="'.$this->option('pace_bd_color').'">
			<TD style="padding: 20px; " class="body-td" valign="top" align="center">
				<table>
				<tr>
					<td align="center" class="smallText">HORAS</td>
					<td colspan="2" align="center" class="smallText">MIN  SEG</td>
				</tr>
				<tr>
					<td align="center">
						<input type="text" name="phr" size="2" maxlength="2">
					</td>
					<td colspan="2" align="center">
						<input type="text" name="pmin" size="2" maxlength="2">
						<input type="text" name="psec" size="5" maxlength="6">
					</td>
				</tr>
				<tr>
					<td>Por</td>
					<td><select name="punit" size="1" class="pulldown">
							<option value="Mile">Milla</option>
							<option value="Kilometer" selected>Kilómetro</option>
							<option value="Half Mile">880 Yardas</option>
							<option value="Quarter Mile">440 Yardas</option>
							<option value="Eigth Mile">220 Yardas</option>
							<option value="1500M">1500 M</option>
							<option value="800M">800 M</option>
							<option value="400M">400 M</option>
							<option value="200M">200 M</option>
							<option value="Meter">Metros</option>
							<option value="Yard">Yardas</option>
							</select>
					</td>
				</tr>
				</table>
			</td>
			<td style="padding: 20px; " class="body-td" align="center" valign="top">Pulsa Aquí:<BR><INPUT type="button" class="pulldown" onClick="myform = document.forms[0]; CalcPace(myform)" value="CALCULAR RITMO">
			</td>
		</tr>
		<tr>
			<td colspan=3 align="center">
				<INPUT type="button" class="pulldown" onClick="var myform = document.forms[0]; CalcSplits(myform)" value="CALCULAR TIEMPOS DE PASO"> <INPUT type="button" class="pulldown" value="LIMPIAR" onClick="document.forms[0].reset()">
			</td>
		</tr>
	</table>
</form>';
	return $calculator;
	}

Alguien puede, por favor, ehcarme una mano.

Gracias