If I had a 75B SA, I would replace the trigger return spring with the one from Cajun Gun Works. Then polish most internals, leaving the sear disassembly for another day. For the $7.00 spring, $13.00 for the TR-PIN Floating Trigger Pin, $8.00 shipping and couple of hours (?) of polishing with tear down and reassembly this should give you a lighter trigger by 6 - 8 ounces and a smooth break.
