Sorry to hear your problems with the Rumour... but take heart that once it's all fixed up, you still have a bargain - that Rumour would come it at over 3k new. As you say, just a bit of a bummer that it requires so tweaking. You've had a Rumour before right - so you know how they can play.
As a matter of course, I'd get it back to Bernie for a once over. These basses are set up to the player so it may need some adjustment to get it to play right for you. Not a lot of people can play my basses because they are too low and rattle too much. For me, with a light touch, they play perfectly. Combined with the fact you don't know what people have done with their basses once they have left Brighton, it may be overdue a magic touch.
From what you describe, its sounds like the strings are too low in the nut for you. I'm sure Bernie will build the nut back up for you and certainly a pot replacement is not an issue. In fact, given the age of that that Rumour, I think Bernie has changed to since changed to better pots (smoother running, electronically and mechanically more reliable) so it may be worth getting it serviced just for that.