speedometer spindle rotating

[Hans Efde]

Hello,
Can someone give me advise on the following. a while ago I lost the speed indication. I checked the speedometer and cable. Both are fine. Today I removed the speedometer pinion, which is on my car a red color coded. It is in good condition. When I go into the hole with my finger I can freely rotate the shaft with gear that drives the speedometer pinion. The engine is in 1st gear so I expected it not to be movable.
Is it normal that I can rotate the drive shaft for the speedometer or must I suspect that it's broken? I haven't removed it yet because that requires a lot more work and I don't know if broken parts then can fall into the gearbox.
Cheers, Hans

[Hans Efde]

As an addition to the upper question, I have tried to rotate the pinion itself and it wouldn't rotate.
Also I want to get rid of a large error in my speed indication, which is 12,5% too low. There are about 5 different pinion-spindle combinations. I seem to have 18/5, the next step is 17/6. But to remove the speedometer error I would need a 16/5 combination. According to the list only 16/7 exists.
Has anyone ever experimented with non-standard pinion-spindle combinations?
I know David is keen on pointing out the merits of electronic speed indication, but I just bought a new surf sail, so not much money in the bank at the moment!

[Hans Efde]

Oh yes, for interest a few websites:
http://www.ime.org.uk/ime/f/final_drive.html
http://www.ime.org.uk/ime/s/speedo.html