If it indeed is operating normally, it would probably make sense to unbolt it from it's bracket , place it upright on a bench and 'split the case halves'.
This way the internals can be inspected (pay close attention to the five drive balls and their respective races).....you'd also be able to then thoroughly clean inside the unit.
If you go this route, it may be wise to contact Paradise Wheels in California and order a couple of 'O' ring seals( to re-seal the case halves)...although if the originals aren't broken or torn they should be reusable.
Post a few pictures of your 'new' Avanti when it arrives!
PS....When inspecting the internals, also look at the output shaft (at the center of the five drive balls), and be sure to clean the brass oil pump screen (it unclips) that the supercharger fluid passes through.