Dave,It is so easy to measure drop across the breaker that there's no excuse not to do it every year. I wanted to see how bad it would get if it were left alone.
The stab contact itself maintained a low resistance that's a negligible part of the total. Most of the heat is generated inside the breaker. It would at worst precipitate a thermal trip. Resetting it would re-seat the circuit interrupting contacts.
I believe that, in day-to-day use, the panel is as safe as ever. The risk is when a tech removes breakers. If both breakers on a stab are pulled, the second one may take the clip* with it, and it could fall onto the bus and arc. I glued them in place, but my private notes include a warning to hold it down with a nonconductive tool. I would have loved to spot-weld them but I don't have the means, and anyway, the bus would be live. Been there done that not gonna do it again. =8)
* A plain brass strip folded over the corrugation to make it resemble GE's new profile.
Thanks for the encouragement.
Gluing them in place?
A stern reminder is in order that the things we do today will outlive us. Whether people have hobbies in tinkering in areas like this or not, it does not give people the excuse to perform modifications or make installations that do not abide by the current Codes, no matter the trade or how trivial the work, even if you are the owner.
In a situation like this, even if you are comfortable taking this risk on in your life, and even the chance of potentially exposing your community to a hazard via overheated service entrance conductors, what would happen if you were to suffer a death via car accident unexpectedly? - you would not be around to handle these mitigated risks you have taken, and now you have exposed a stranger to a potentially life-threatening situation.
Let your hobby coincide with safe installations and practices. Leave this world a little better than you found it.