Replacing seals is the first step, inspect the rotors and cases. I think this is a dual pump - one for the engine and one for the transmission, but I'm not sure. If it is, the larger rotor set is for the engine and the smaller one is for the transmission.
There is a spec for end clearance between the rotors and case, easy to measure with plastigauge. Over spec can probably be tightened by machining the case or cover. The other spec is for rotors to outer case, a feeler gauge job. Clean the bypass valve assembly.
The trochoid rotor condition is not super critical, I have never seen a used one without damage. If they are not super gouged up they're probably OK. End and outer clearance is most important. You can use an oil pressure gauge to see if your pressure is low... but that is affected by bearing wear as well as pump condition.
Internal hard parts are not available, even the seals and O-rings were not sold separately for most Honda oil pumps . Any used pump available will probably be less than pristine. Message Elan about the O-rings, if there's an oil seal in there it may be a common size...
