A pinhole in the diaphram is definitely NOT normal and probably cannot be repaired. I think the time may have come for you to go ahead and take the pump apart and take a look at the innards. Be sure and notice where ALL the parts are supposed to be and be very careful to not tear the diaphram or lose any parts, then eyeball the diaphram looking for holes. I don't know of anyway to repair a diaphram and don't know if other OS pump diaphrams will fit. If you can't repair/replace the diaphram it may be Perry pump time.
Good luck.

Regards,
doubledee