One mor vacuflush question

[madhatter1]

Pump was cycling. Traced leak to head where actuator goes through the side to flush. Series 800. Looked up parts diagram online since book seemed vague on parts. Found same diagram online. Only part I can see possible to replace is the cartridge part number 385236096. But the issue is leaking air into system. I don't see any seal on the cartrige or available on the parts list. Is there something I can reseal myself? Do I need a new bowl assembly?

I guess I am lucky that fix is here and not an issue down the line. Usable now but I need to fix soon.