Did the bass come with a long/lifetime warranty? If it didn’t, expecting it to be sorted out 5 years down the line, after 4 years of trouble free use, might be asking a bit much from the builder’s point of view. Did SIMS say it had been made badly at all? We all, myself included, want ongoing, trouble free ‘mileage’ from our instruments but, unfortunately, sometimes things just fail and we have to get them fixed.
I’m not having a go, BTW, just looking for a bit more insight/playing devil’s advocate.