Am in the process of disassembling a M50 injection pump that mounts on a Mep 003a generator. Like others I do not have the " pressing tool " for removal of the plunger retaining rings and seat. Have seen mentioned by others a customized " socket or pipe " tool that works. See in the pump disassembly guide ( figure 4 ) what appears to be a cutout that enables one to access the rings. Questions : Does the pressing tool sit on top of the spring seat ? How tall of a cutout do you need ? How far does spring seat travel before rings are visible ? Any other pointers would be greatly appreciated.