Did not like the hollow plastic grips on my 1377/2240 so after watching the ad on TV about Flex Seal liquid rubber I went out and bought it. Filled the hollow grips on all mine; let it cure a couple of days and I am a Happy Camper!
Pull it into something like a small paper cup. Then fold a spout on to it. Pour carefully,only until level in the grip! Hardens into rubber when completely cured.
If you spill any it can be pealed off later. If you get any in the checkering jewelers steel wool will clean it up after it drys.