I've always used Scrubbing Bubbles Mega Shower Cleaner for knobs and plastic parts, aluminum I.F. can covers, whatever. It is first rate at removing nicotine and tar. It might be a little on the pricey side, but the trade off is Zero elbow grease. It might also remove some painted areas, so please test on areas that won't be visible first. I just put the parts in the laundry tub, spray liberally, both sides. Let it foam up, and completely cover the parts. Walk away and come back in 20 minutes. You will not believe the CRUD that comes off. Rinse parts in warm water and blow dry any crack and crevasses. Give it a try you will be amazed. I've also found the "lesser Scrubbing Bubbles products" ie. "pump type" don't work as well as the Mega Shower Foamer. Oh, ya, this is just my 2 cents...
https://www.walmart.com/ip/Scrubbing...unces/14862641
Bob, that is just NASTY, I can almost smell it from here. Good Luck with the set.
Tony