same here, you solved many errors, maybe another cleanup with better products, contact cleaner must not leave any residue or oil / lubricant
and maybe, just maybe try to get better resistors values as kleinstein wrote to tests all possibilities, and slowly redo all the tests / current generator etc ..
this meter has gone thru a lot, be sure the front and rear switch is good too, it can play some tricks, there was some who had relay problems on one coto model ...
be patient and do things methodically, you'll get there, and lucky you schematics are known ...