Hi I’m about to purchase a second hand slim phatty which lacks 2 pot caps.
Are those standartized? Can I use any other cap or is there a chance to get replacement parts from Moog?
Also, would it be difficult to remove the two caps left? Would look terrible otherwise! 
Please answer, the auction is about to run out, thank you!
Are you referring to the front panel knobs?
If so, the SP uses two different sizes, and you would be better off ordering replacements from Moog than trying to piece something together.
However, FWIW, to be honest I would be more concerned as to WHY two knobs are missing.
Makes me wonder if something happned that required the knobs to be replaced in the first place, and if so, if the controls they are supposed to be attached to are functioning properly.
I own two SP’s and an LP, all VERY good quality, and to be honest I have a hard time understanding how knobs might just fall off and disappear…
Randy