Hi all, I was a member many years ago, and decided to become one again, as I'm fixing up my Polaris after a dozen years of gathering dust. I bought it about 18 years ago, I think for about $100. It never worked perfectly, but after some membrane trimming, it worked well enough for a few years. I didn't know what it was when I bought it, but I could tell it was a real instrument, and not a toy.
I read online about someone who soldered wires to the membrane ends. I did that to mine about a week ago. It took a couple of hours and some sweating, but it turned out well (except the 3-pin strip that was extra brittle, and required trimming through to the front/top. My soldering iron has a minimum setting of just under 400F. I found that if I kept the soldering iron above the membrane, and added solder in-between, it usually worked okay. I used thin wire, and tacked on Vero board strips to act as intermediate connection points for the wires.
I finally got the Sysex patch transfer working. I was being lazy, and instead of getting out my proper interface, I used a cheap USB-to-MIDI converter... but Sysex didn't work with it (although notes and even patch changes at start of play seemed to work). Up next is battery replacement, sliders repair/replacement, and then a good clean-up.
Anyway, I love this synth. It sounds great, is powerful, and has great character. The control via sliders is a plus - much nicer than knobs or buttons.