Yesterday I changed the plugs in my 2002 620 Dark. There were no Champion plugs around, so I bought and used the ones that were listed as compatible on some website (www.sparkplug.co.uk). The tread is fine, and they work fine, but the rubber cover that completely covered the old plugs does not cover the new ones, since the non-electrode end of the plugs is a different shape. Basically, a bit of the spark plug is exposed/. Is this dangerous? Thanks for any replies!