Have you ever noticed that after you clean the slugs good and reinsert them in the threaded holes, they are a little loose? So when you do an alignment, any little vibration or bump may throw off the adjustment. I've seen pieces of thin plastic or rubber strip between the slug and thread before when taking them out. That's how the factory made them snug in the hole. A lot of times those can jam and you end up breaking the slug if your not careful. What are some of the known tricks of the trade by amateur restorers for solving this problem? For example could you a light coating of vaseline or something to make them a little more secure in the thread? And whats a good adhesive to use, besides wax, when you're ready to seal them up after your done with the alignment. I would be interested in how other people approach these issues.

If you'll notice on some slug-tuned coils, the manufacturer put a little spot of glue where the threaded screw enters the "nut" equivalent on the coil case. It's just enough to keep vibration from moving the slug but can be overridden if required for readjustment by picking off the glue.

For the ferrites that are not adjusted by a threaded screw, I would just use
a drip or two of soft wax. Many of them (as you mentioned) have a bit of
rubber strip, like a chunk of small rubber band, inserted. I would not be
tempted to cut up a rubber band to replicate that, because the rubber bands
nowadays seem to deteriorate very quickly.
An alternative might be a very small strip of paper, just enough to stabilize
the ferrite core. It's no problem to find all kinds of paper in different weights
and get one that works.
I like to borrow my wife's nail polish sometimes... ask for a color she doesn't
like...
Nelson

...or you can go in the dollar store and pick yourself up a bottle of nailpolish cheap, looking the clerk straight in the eye as you check out...

Sewing thread or dental floss inserted will keep the slug from moving about or falling out.

You can either drip wax from a candle onto it, or use a removable type of glue. I use a gel.

Beeswax or candle wax. In the days of yesteryear, something called "Faraday's wax" (a mixture of beeswax and rosin) was most likely used. It's not brittle like candle wax, it's a very soft and sticky, pliable material.

I have a friend that uses the red wax that comes on the outside of Dutch Edam cheese. Works well, and you can always identify his work - only problem is, when you put your soldering iron onto the ferrite slug to soften the wax so you can re-tune, the smell of cheese is somewhat off-putting. True story!

Do I understand you correctly? Are you removing the slugs from the forms and cleaning them, then reinserting? If so, can you explain why? Sounds to me like you are just asking for trouble.