Long arcing on the root is not some big secret problem that needs a deep fix. Half inch off the plate is a lot, yeah, but that is just basic arc length. Every guy learning sticks deals with it. Not saying your old timer was wrong, he gave you a solid tip. Just seems like you are making it out to be some huge embarrassing thing when it is really just normal stuff that happens when you get in your own head. Three tries on a cert test is nothing, plenty of good welders took more than that. Tight arc is rule one and sometimes you just need somebody to say it out loud.

Old drives like that just keep going when they stay cool and get used steady instead of sitting idle for months. Heat is the real killer, so that Phoenix glovebox probably baked the bearings worse than any normal use ever could, yet it's still here. At this point you just run it till it makes noise, then swap in a flash card and stop worrying about it.