Dish only needs to have moved 5/10mm in any direction to lose signal( it’s my jobs to install them)
It could have moved but to be fair it doesn’t happen that often ,if it’s old it’s more likely that either the LNB on the end of the dish arm has failed or the box has give up.
Are you able to borrow someone’s box to connect to your system ,if you then get a signal/ working set up then it pretty much proves your box is dead,plenty of cheap replacements off eBay, may even have one myself wink,wink.
The only other thing could be damage to your cable from cuts,crimping,piercing ,water ingress ,it’s worth having a good look at that too.