Stack Dash Question

[culminator]

I've not long had my car and shortly after buying it, I had to send the Stack dash off to get a new internal battery fitted. Anyway, got the unit back, fitted and now I've noticed that the tacho needle moves quite "jerkily" and not in a smooth arc. It's particularly noticeable when the revs fall and there seems to be a slight delay.

Is this normal or have Stack introduced a problem to my unit?

[culminator]

so do most 7's fitted with a Stack Dash behave like this? I'm not overly bothered about it but want to be sure that I dont have a faulty tacho now.