Hartell pump ltp-1 troubleshooting

[Hughpe]

Hello,
I have a Hartell ltp-1 pump I use for my utility sink/ clothes washer.
Sometimes the sink fills up by the pump does not kick on until I give a light tap on the PVC vent tubing. Should I take it apart to clean it , replace the float switch. Any suggestions would be helpful.

Thanks,
Pete

 

[Reach4]

I don't know if these will help:
http://www.hartell.com/Hartell/en/RESOURCES/FAQ/Q2 is for the opposite problem, but the cleaning might still fix your problem.
http://www.homedepot.com/catalog/pdfImages/c0/c0e17ccf-e7d4-468a-8217-f05f10b2252a.pdf
http://www.wholesalepumpsdirect.com/store/p/749-Hartell-LTA-1-Replacement-Switch-Kit.html