Yes and if the belts are original, they're usually the consistency of tar and no, I'm not joking.
One 950 or 955 that I refurbished, the reel belt melted into the take up reel spring which was a pita.
It's fairly tough stuff to clean up.
I forget but I believe acetone cleans it best but you have to be careful what you use it on as it can melt certain plastics.
Something safer like mineral spirits might clean it but it takes more effort.