Inconsistent firing of Profoto B1

I was just wondering if anybody is having a similar issue. I've noticed my B1 will fire a very over exposed flash periodically. In a set of

about 30-40 shots, three to four will be greatly over exposed. There's no consistency and I don't see any pattern to when it happens.

However it's never two in a row.

<p>Which camera? And is it with the same lens? (exif info for the shots will tell you).</p>

<p>I had a similar intermittent situation ... which turned out to be a sticking lens aperture. Rather than stopping down upon release, it stayed wide open and grossly over-exposed the shot with the B1. </p>

<p>- Marc</p>

<p>Also, TTL mode or manual mode? Manual should be dead-on consistent barring equipment failure—TTL can bounce all over the place depending on what the camera decides the correct exposure is at any given moment. </p>