I just bought a Husky 640 and while working the action with dummy cartridges, noticed a problem with the safety. About one third of the time, the safety jumps into the upright position when the gun is"fired", preventing the bolt from opening. The gun appears little used but there is wear on the safety engagement surfaces. Do I need a new safety?

You should have a 98 action; after the cocking piece falls, the safety can't jump up.
So whatever is happening with a safety is not good; have to send to someone who knows Mausers.

No expert but it looks like a 96 to me. Maybe it's not a 640 . 96 style shroud and safety. Cocks on closing.

Ok, then that can happen on a 96.. Put some RTV in the safety hole in the bolt shroud and that will dampen it. Commercial safeties have little knubs of nylon inserted into them to keep them from rotating.
Swedish Bubba was fond of grinding and welding their rifles and yours has the safety ground, allowing it to bounce around. A new safety lever will help too. I have had at least a dozen of these...

I'll PM you.