Hello there!
I rarely use Voltages above 10 Volts, so the discovery about this specific problem was kinda random (testing a DC power supply). With 50 VDC input, the meter jumps rather random between values like 22, 26, 34, 28 or sometimes nothing at all (blank). If i hit the 70+/- VDC mark, everything goes back to normal operation. Same with 14 Volts or below. So far nothing was changed within this specific meter (no caps, no nothing). Its rather untouched including the superb fan of unholy loudness
Problem starts around 15 V input and stops at around 70 or 80 Volts DC ... between 15 and 80 it seems kinda "unstable". Sometimes 60 VDC input shows at 60 VDC, sometimes not. It seems to be within spec with 10 Volts input (compared to other meters 5-6 digit meters) or 100 VDC input. Mayhaps this small clip can help to "illustrate" the behaviour.
I'm thinking about some dodgy relais or switches, dunno.
Best wishes from germany!