Graaf Power Amp Info Needed

I borrowed my friends Graaf 5050 tube amp 50 wpc push/pull design. It sounds very nice but this model is no longer made and has been replaced with GM-100. I have concerns about buying one and getting it repaired in the future. Does anyone have experience with Graaf tube amps? What other stereo tube amps would you recommend and why.

Thanks and Happy Listening.