You'll need at least an o-ring for a pump swap. Here are the parts I see in the EPC:

016 997 32 48 pump main o-ring
016 997 37 48 cut-off piston cover o-ring
126 277 08 55 cut-off piston big teflon seal
126 277 20 55 cut-off piston small teflon seal

NOTE - these part numbers are based on a difficult to read EPC screen.

Sixto
87 300D