Years ago, a lady friend had bought a used 1967 Firebird 400CI, 3spd. that the former owner had hot rodded.(solid lifter Crane Cam). After driving for about a year after I had reset the rocker lash to specs and WOKE UP the engine, she informed me that the starter had quit. After pulling the Starter/solenoid four successive times (this was before auto store testing), I was reinstalling the battery cables when the radio suddenly blared! I had forgotten that I had left it turned up along with the headlight high beams and blower fan when I checked the low drain battery loading prior to the last starter R&R. Inspecting the bolt-on battery terminals I found that corrosion had built up INSIDE the cable itself. Thankfully there was enough cable to trim back about 1" and reinstall. Starter problem CURED.
Thanks for the tip.
I’ve also seen side mounted battery posts broken inside the battery case and causing intermittant problems.