Does anyone have experience with troubleshooting a power trim for an I/O?

My 1974 Searay 188HP MerCruiser will not hold up. There are no leaks in the
cylinders or in the stainless flexlines and I have not had to refill the
pump reservoir. Does anyone know if there are replaceable gaskets/O-Rings
Inside the pump (i.e. rebuild kit) for power trims?