Imo, the death of the chainsaw falls on customer C’s for running subpar fuel in a 2stroke to begin with (the most likely series of events: seals go, develops air leak, carb runs lean, rings bind)

Ethanol-free fuel, 92 octane (you’ll know it’s right cuz it’s like $6/gallon- don’t buy the premixed shit in the store, find a proper station) properly mixed with oil, can run all day, never a problem.

But that’s just my opinion