Help with 41CL and printer

[BobVA]

You might try gently squeezing the calculator halves together in the area over the upper / battery block connector and see if that makes port 3 and 4 start behaving.
If so, you can try cleaning that connector, or just gently tightening the upper screws, but yeah, there's always the risk of damaging the posts.

There's a variety of techniques for repairing the screw posts if it comes to that. I had luck with this approach with some cautions here.