Ironically, I just logged back in here after a few years about this same topic. Fighting with the buttons and the display window is burnt so you can barely see the screen during the day. So far, only thing I found was someone on ebay offering to repair it for a lot of cash, which if that's the case, I plan to try myself. I have done a few tv remotes with similar issues with mixed success.
Another option I was investigate was remote control. I thought I remembered the tub had a stereo option, and if you got that option, it came with a remote control. I wonder how much to "retrofit" the tub to use the remote would be, both in labor and cost.