Just remembered some peeps coat them in silicon or evostick type glue to solve the problem it sometimes works but looks s**te
I tried that on mine and couldn't get it to seal, plus like you say it looks s**te. Nice shiney new rubbers sorted mine but wasnt sure if they were still readily available. Zacs is just down on power under load now though, think my rubbers cause erratic running/tickover. Must be 20 years ago though so anything I may think is suspect