Own 2 sl1200’s w couple tweaks, and the mid 90’s 1210 black version.
old ones are oiled, cleaned, kept unplugged, then warmed up before use.
35+ years old on silver o.nes.
20-25 years on black. Never any issue, ALWAYS START AND STOP.
I will be handing these down to family someday, I know they will work, I take,care of my stuff