I don't have any stories quite like that with bass gear, but a couple stand out:
I once had an input jack go bad on my Morley Diamond Distortion (long gone but in the late 90s it was my favorite overdrive for bass, I used it on many gigs and several albums). I called the company and asked if they knew where I could buy replacement jacks, as it looked like an easy job to do myself if I could find the right part (had to be the right one as the circuit board was mounted to the jacks). After confirming that I wanted to fix it myself, they asked for my address and a week later I had a replacement jack and an extra for free. Just a cheap part and I know cost them pennies, but I had expected to get routed to an authorized repair shop and pay through the nose.
Some years later I was using an Eden head (WT-300 I think) that developed some crackle in one of the tone pots. I popped the lid and found that the way things were mounted it looked challenging to get at the pots for spray cleaning. I called the company and quickly ended up on the phone with David Nordschow himself, who was still at the company at the time. He talked me through how to do it at length and recommended his favorite product for cleaning pots (unfortunately I have since forgotten what it was). How often do you call with a service question and get to talk to the guy that designed the thing?