Hpi saveage with dynamite mack 2 28 the shaft that go on pin on crankshaft keeps slipping off

[Joe w]

Hi i have hpi savage with the dynamite 28 mack 2 motor an I'm confussed but the rod that gos on to the pin that on the pistion rod keeps slipping from the rod that gos into back plate that 1 way gos on y

 

[tntpoof]

can't seam to remember pin here point it out plz.
DYN0700-Manual2.pdf (towerhobbies.com)

 

[monstertruckier15]

If it's slipping then it's worn out or you put the one way shaft in the wrong slot. Or the stub shaft for the one way shaft is broken?