Yamaha RS remote system compatibility

Hi, I have a Yamaha AVX-100u integrated amp with no remote. It is from c.1989 and has the "RS" remote symbol, wondering what other remotes from Yamaha would be ok to use since it seems impossible to find the original model. Basically I'm wondering how cross-compatible other "RS" remotes from other "RS" receivers/amps might be? I know I can go the aftermarket route but would like to attempt a stock remote first. Thx!

My CX-2000 Control Amplifier originally came with an RS remote. I’m using a Yamaha RCX remote with it (from Ebay), it works fine. It’s a leaning remote, I was able to program the missing commands (like “Source Direct”) with my AVR (RX-V1065) remote.

I ended up breaking down and getting a Logitech Harmony 650 universal remote (which I absolutely love!!!) but I'm keeping my eyes out on eBay for other Yamaha remotes from the same vintage on the cheap.