Cleaning threads for heater anode

[Cracker]

Is there any way to chase the threads on the anode assembly? It looks like there are calcium deposits that are preventing the anode from being screwed into the heater very far. I believe that it will seal, and I know that the threads are tapered, but it doesn’t look like any more than four threads go in before it gets tight. ——and yes, I’m using Teflon tape. This is a “new to me but” used travel trailer. Would CLR do anything?