[morzh]

Take the cap apart, rotor and stator separately, soak in dishwashing soaped water (not together), take a long soft brush, gently brush inside. Rinse well, blow with air (be careful with airguns, better use canned air), dry completely.
Reassemble, lube.

The dial could be washed with mineral spirits. Try on a corner first.

Find the grommets. The ones you have are fully flat. The grommet should be 1) a bit thicker than the metal insert, 2) allow the inserts to go through and 3) be able to go through the openings in the chassis without being torn apart (heatgun on low helps by softening it). Renovated Radios might have them . If not, bu a suitable grommets in Lowes and use rubber washers to pad if not long enough. This is a bit tedious to reassemble but I did that a few times.