To be truthful, I don't drink tea.
The old saying used to be -- we can put a man on the moon but we can't make a teapot that doesn't drip when you pour.
Anyway -- back to Dremel.
I have been nursing my Dremel along lubing the bearings with a product called "Power Up". (Don't know where you get it or who makes it). I bought a gallon of it for 70 dollars (pricy) about 10 years ago from a traveling snake charmer. The demo was that impressive.
It will take grinding bearings and they will run smooth again.
(Or at least so in my Dremel). But it is hard on rubber,gaskets and such.
I also had the switch burn out so I opened up the Dremel, removed the switch completely, jump wiped the contacts so it would run full RPM when plugged in.
I then took a 5 amp variable speed controller and plugged my Dremel into it.
I do not get the variaty of speed control that the original Dremel switch gave me, but I do get what I need. Full RPM down to about half.
The main reason I did this --- one look at that switch and I knew it wasn't worth the money to replace it.
I don't recommend anyone fooling around with wiring, unless you have electrical know how.
I am not saying I do -- just saying I like fooling around with wiring.
No , I don't have my first dollar, but I do have some of the change.