i have a CT122 bobcat tractor. the fuel filter keeps on collapsing inside the clear bole it is in. I have done everything i know to do : took the tank off and cleaned it just in case any dirt was in there, took of the housing where the filter attaches to. took off the hoses flushed and blew them out, got fresh fuel from different place. I even got a new vent fuel cap for the tank. The new filter I put on is starting to do the same thing. This has me baffled. Any suggestions as what the cause might be??