Hello,
Your post has been much help so far, and I need a little more direction. So, when I depress the flush button, I can hear clicking, as though the pump engages, then stops, then engages. I have removed the pump, manually turned the impeller, reinserted and tested. No luck. The impeller did feel like it still had some resistance. I can feel the motor engaging when I depress the flush button. Do I need a new pump?

Robert E. Lee III, May 2011

it would have helped a great deal to tell what make of toilet, there are ones other than Thetford.

it could be the micro switch/es it could be the pump or it could be a bad connection in the cable run to the pump. howerver follow info below.

for access to thetfords free downloads on repairs.

uk & europe www.thetford-europe.com
australia www.thetford.com.au (even get request from australian campers)
australia site has stockist list.

home page select english {if in australia forget this selection it doesn't come up)
select customer service (top line)
select products from top line
select bulit in or portable which ever applies.
select user information from list on right.
select repair instructions from list on right
select built in or portable which ever applies.
select select your toilet series model number from right list.
you will now be in the pdf listings for your range of toilets just select those that apply to your toilet and down load them they're free.
as you go through watch for 'ask thetford' on left listings
you may not find what you want and you can send them a message.

for safety reasons which i agree with thetford do not offer repair advice for fridges. refer to service centre

bob, May 2011