Need help identifying and finding similar SMD variable resistor
They're similar to obsolete Panasonic EVM1U 4mm trimpots, though without accurate dimensions it's hard to tell. 



It does not look damaged, it might be corroded or it could just be cosmetic corrosion of the Ag plating. 

It's obviously connected as a rheostat. Note the current position of the wiper and turn it back and forth from end to end a few times, then return the wiper to the previous position (with power off) and see if that makes any difference.

You could also probably replace it with a 22K resistor if it's really bad, but if cranking it end-to-end a couple times makes no difference your problem is probably somewhere else. 

Be careful to get a tool that fits the trimpot properly and proceed gingerly, it's easy to damage those small parts with ham-fisted twisting and thrusting.