I've seen things made deliberately awkward before so that the servicing didn't go elsewhere and the 'magic' was kept inside. Left handed threads etc

Everything can be opened, it's just an application of time and knowledge that costs. Sometimes it's more economical to do replace a whole unit, but that's annoying when out of warranty. I had a car which was under warranty and the clock on the instrument cluster would run 10-15 mins fast. I mentioned it at the dealer, the whole instrument cluster was replaced. It was quicker to do that than train someone to take the thing apart further and replace that part and put it all back together and back in.

Fx seem to have a strange reputation.