UT61E DC voltage measurements problem

[Buhefade]

Hello
I tried to dig through Ut61e posts but I wasn't able to find similar problem
-On DC voltage (both auto/manual) display can't be zeroed even when probes shorted (shows small negative voltage)
-gives different results when probes switched. Example: read out +4.5V - > switch probes and same potential read out - 2.4v.
-measurements are not sonsistent in overall.
Tried:
Board nad main switch cleaned
VR1 replaced
Corrected soldering around main IC

[Mickle T.]

If there is no contamination on the printed circuit board and on the switch lamellas, then I see only two reasons for the zero shift of the multimeter: failure of the auto-zero correction capacitor C6 470nF (pin 14) or breakdown of the input circuits of the ADC U1 ES51922.