I had three failed GA5010's.
Two of the three had failed trigger switches, to the extent that the plastic trigger switch had burned up. I assumed the contact points in the switches had deteriorated and , arced, and burned. However, the position of the burning looked odd.

So I opened up one the failed (burned) switches and the contact points looked great. What had failed was the contacts between the sliding assembly and the top housing, While the switch is designed to "slam" the four contact points together when the trigger is pulled the sliding contact with the housing must gradually where down, get dirty? who knows. These then heat up and start melting the switch.

This does not really seem like the safest way to fail, if there is one.

I suppose if a person had some indication the switch ws going downhill, you could take the switch apart and clean it. When my replacement switches arrive I will take aprt the one which hadn't burned up yet and look at its' sliding contacts.