Erratic chronometric

[Oggers]

Gents

Smith chronometric speedo on a 55 Velocette MSS has developed a fault. Basically it is reading very low - reads 10 mph when shoud be 40 or so. Mileometer works, cable looks OK, no sharp turns or kinks in the cable. Fine yesterday!

Clues appreciated.

Thanks as always

Mark

[R]

Are you intending to diy, or take it to a specialist ?

[Oggers]

A few drops of wd40 seems to have sorted it....I like simple solutions.

[Rex]

From what I've experienced and read over the years, the grease used on assembly goes hard and stops the finely-tuned mechanism from incrementing and returning. Presumably the WD40 softens the hard grease enough to allow it to work as it should.
 Whatever solvent is used never ever get it on the drums or face as the numerals smudge and fade very easily.

[iansoady]

s the numerals smudge and fade very easily.

Yes, I can endorse this having ruined a trip drum many years ago.