The screen on our Tektronix TDS210 was lacking brightness and contrast, so we thought it was probably the backlight.
After some trawling around online we discovered it was fairly easy to replace.
Unlike the later electronic synthesisers which employed oscillators to produce notes, this instrument uses tuned metal reeds. Each key is connected to a small rubber pad, which ‘lifts’ the reed to set it vibrating, and each reed has its own individual pickup coil, which provides the signal.
While refurbishing my 1989 VW Transporter T25, I discovered that the spring clips which hold the halves of the airbox together were so badly corroded that they were unusable. Crumbling to dust would be a good description of them. I tried various sources but could find no replacement which claimed to be for this specific vehicle