speedo drive dustcap question

[DB-1584]

Just discovered that speedo cable is missing its clip where it goes through the dustcap on the nearside hub, have got clip now.
Noticed that the dustcap spins freely, should it do this or should I give it a burr or two to stop it rotating?
speedo was under-reading by 5mph, was wondering if rotating cap was causing this?

[pieman1]

Mine is a tight fit ,you can’t turn it by hand.

[DB-1584]

I'll tighten it a bit then, nice one. too much grease about the place probably.

[nevill3]

It's also recommended to seal the hole where the speedo cables comes through with some gummy stuff after you place the circlip on to prevent water ingress. I have just replaced my speedo cable to cure the annoying bouncing speedo needle and on a recent motorway trip I found that my speedo reads 10% out, this is quite normal.