Fuel pumps stops working

[sf38a1]

M38A1 Military Fuel Pump . Rebuilt it over a year ago . been running fine . A few weeks ago it stopped pumping fuel . pulled t and disassembled it . The Fuel pump diaphragm fell out on disassembly . Check ou all parts everything look good . Reassembled the pump , and installed . Ran it for 4 days ,short trips , to the store , work , no issues . Coming back from an event , it shut down . Got it home and took it apart . the Fuel pump diaphragm had unhooked from lever again. this time i Look at the square hole on the diaphragm , was angled on the bottom ,like a scissor blade . I used a file to square it out . I reassembled it and it seems to work ,for now . Any one else have a issue with the fuel pump diaphragm becoming unhooked from lever ? and what did you do to correct it ?