Onan Propane Genset issue - won't stay running

I am having the same issue the gen will run fine one day and then will only run if button is held down the next. Whats funny is it ran fine everyday the temp was below zero and then when the weather warmed up it would not start again. Took the camper to onan and it started right up and they cannot duplicate the issue. I cannot find the onan lp 2500 service manual online anyone have a link or can send via pdf