smd precision resistor "paint layer" peeled off while soldering *** advice need

[rodd]

Dear all,
I was doing a A5 board repair of a Tek2465BCT I bought some time ago.
This is a late unit, serial # B0577746 and the A5 board is the 671-0965-05.
I inspected the board when I bought the unit and there were no signs of corrosion, so I left it as received for quite a long time.
It seems the caps have been replaced ( I can't say for sure) but the board was not cleaned well enough so the corrosion started.

Near the ADC (U2101) the only pads "missing" are the ones for C2520, but I had to remover and solder again some SMD components in this area.
While doing this the "paint layer" of R2012 (RES,FXD,FILM:10KOHM,0.1%,0.125W,TC=T9) fell off, exposing the tiny traces.

I could not find a direct replacement for it so I am thinking of leaving it there and apply a layer of some isolating material (PCB varnish, for example).

My question is: Is it possible the the varnish would react with the exposed traces, changing the component characteristics?

|Is it better leave the component as it is? Any other coating material suggested?

Thank you in advance,
Roger

[drvtech]

I think you should coat it with a varnish or conformal coating, but one which is specifically designed for use on electronic components. And you should be sure it is scrupulously clean first. If you don't then water vapour and anything else in the air will eventually react with the resistive element, changing its value at least. If it's a precision resistor then presumably a close tolerance is required otherwise a standard part would have been specified.