Some profoto questions! HELP :)

[shortpballer]

I just bought a Pro B2. And I tried using it with one of me Pro-B heads and the modeling light won't turn off. its not the B2, because I have two of them and they both do it. But when using a pro-7 head it works perfectly fine, because the pro7 head has a modeling light switch.

Another thing is that I noticed my pro-B head gives off about a half stop more light than the pro 7 head? The flash tube on my pro-B is almost brand new, while the flash tube on my pro7 is quite a bit older and a little black around the contacts. Could this be why?

Any help would be awesome!

Thanks,
Eric