help with my perkins

[iwhotoo]

I have the original perkins gas gen in my 79fc35. tried to start it the
other day. The starter sometimes just spins without engaging. I took it
off and tested it with a battery. It spins ok but the mechanism that
pops out to engage the teeth to the engine doesn't pop out. Am I
testing this correctly? Any tech tips on rebuilding this? Also, where
can I get carb kit, and other parts? I have a 4k gen from my first RV
but don't want to swap out because the perkins puts out more juice. Am
I wasting my time?

Mario Barrios
Orange County, CALIF
'79FC35