None I have seen had a filter.
There are later model pumps that did have a filter, and I think it can be replaced with a pump that does, but factory, no filter.
Are you having a lift problem, or just doing maintenance?
Those are known for getting water in the gear cases. It usually doesn't cause problems, but needs to be drained and changed. A bad shifter boot, a bad draft link boot, condensation are the usual causes.
A slow, jerky lift is a sign of a bad pump. A weak, rapidly falling lift is a leaking cylinder seal, blown stand pipe orings, or a bad pressure relief valve.