Many years ago I purchased a nifty little side draft diffusion pump (it's really an aspirator) which was my first major upgrade to my vacuum system. As simple as it looks it's really quite a good item.
After many years of operation (aka abuse) and doing stupid things like leaving the heating plate on all night a heap of burnt oils and who knows what covered its inner walls which are particularly hard to reach. Then I added to my misery by attempting to clean it with various solvents, brushes, and fire. Later Tom tried Citronox which is supposed to be the best. I even broke it's inlet in the process. It finally was put to rest where it sat for years. One day I decided to contact SVP. Mark said it was about the worst he'd ever seen (yay, I'm best at something) but he'd give it a try.
Here is the before photo. It was too dark to even see if we had oil in it.
And here is the after photo. Mark apologized for the slight discoloration at the bottom he could not get out. It's barely noticeable. He restored the compression fitting and fully annealed this pup.
Thanks Mark! Great Work!