Showers/tubs should have a access panel on the other side of the wall the faucet is on so you can get at the plumbing. Mine didn’t (also 1960’s house) so I cut an access hole and got one of those spring loaded wall hole covers that are designed to allow wall access without cutting every time.
I did that yesterday, didn’t fix it. I was able to got the update from Newpipe directly today but my Boo had it three days ago, he said he got it from GitHub? No idea how to do that but maybe worth a looksy.