The brutal winter may have taken it's toll on one of the meters of my home built Helm instrumentation panel. I noticed also noticed a lot of condensation inside the plastic face of the panel even though I had a weep hole in the bottom of the case. I'll remove the panel and check on the wiring and replace the meter if it does not come back to life.
I went back on board a few days later and discovered the meter that I thought had failed during the winter was now working. So it looks like I might be able to take it off the TODO list.