HP48: Rubber Cap for Serial Connector?

[JDW]

I don't yet own an HP-48 (mine is a 28S), but I have read that dust entering the HP48 can cause problems with the LCD (i.e., intermittent connection inside). With the HP48 having been so popular all these years, is it really true that no one ever came up with a rubber cap that perfectly mates with that connector? (I've seen people use tape to cover it in some online auctions.)