Following instructions similar to these on RetroFixes.com, I pulled apart my childhood Nintendo with a special screwdriver bit I picked up from Amazon, and adjusted and cleaned the pins that the cartridge contacts sit in.
It was a little nerve-wracking with all of the screws, but I kept careful track of which ones went where.
Cover is off as of last weekend
Removed the shield, and learned I need Brasso. Nothing in the house is good for brass contacts.
Got my Brasso. Pulled apart a test cartridge to clean and test results with.
Jordan, my classically trained son, watched closely, and helped me playtest the results. Play test results: need to tighten the pins some more, but there’s less already less struggle to get the game going.
Once the final adjustments have been made, most every clean cartridge fires up on the first or second attempt. If a cartridge misbehaves, I clean it with Brasso, and it’s as good as new!