Xcelorin Sensored Speedo Problems Help needed

[tiny tom]

Out racing and my speedo was playing up with not been able to get the power down, it was cutting out and not getting full power. And it stopped dead 2 times in a final, and then started again after a few seconds.
Now someone else had the same problem with 2 of his speedos and he was having the same problem as me. But my car was working the week before, now 2 cars having the same problem on the same day?
Has anyone else had the same problem? Needed help