I use sewing machine oil. It can take a bit of time and effort but the finish on the machine remains intact which is important to me.

I just got some off a 404 with a bit of sewing machine oil and a fair amount of good ole elbow grease. ;)

I have had some ancient tape stuck on machines before. Goo gone, sewing machine oil, or Tri-flow helps get it gone. Some times it comes off all at once some times you have to pick it off with finger nails if you have any after working on machines.

I have found that rubbing alcohol works for removing dried masking tape adhesive. If you tape some thing up and forget to remove the tape within a reasonable time after painting say masking around a window, the tape comes off but leaves this dry hard gunk, like on the FW. alcohol will take it off. I was thinking that the oil drip pan of the other posting might clean up with alcohol too. You sometimes have to let it soak a bit.

The rubbing alcohol will remove some finishes from some of the machines.

I bought a 1937 FW last week that was filthy! I used WD-40 to clean it up. It will not hurt your machine, but always test any product on a small spot on the backside and never rub very hard on the decals, just incase the clear coat is not intact.

I'm sure I have heard hairspray moves sticky after Xmas decorations. I think I would try Vaseline and see if finger power with it will pull it off.
PVa glue which dries sticky comes off hands with rubbing with a small blob of Vaseline to keep little lunricatiom.any way good luck.