If aquamagic sl, sh ,gl , or gh model toiler with 2 pedals at 5 oclock position, you have debris in nylon slider path, Thetford tool 33011 bent screwdriver will clear it out without disassembly. Or use long l shaped allen wrench with visegrip on long end and get short end of allen wrench horizontal and open slider with foot pedal and insert tool at 5oclock pos. and turn visegrips clockwise swiping debris out of just below rubber seal in the path that the slider goes. Just do not drop it into toilet or waste tank! Thetford tool works best and any dealer in the know will know about it. You will find this tool works for handymen for a lot of uses.