uneven development with divided pyrocat in drums

I've been developing film in print drums for a while and never noticed any uneven development. I've used D76, HC110 and Rodinol (1:50). Now I have some shots that I believe I grossly overexposed so I decided to try divided pyrocat to limit the development of the highlights. It seems to be working except I'm getting more development on one of the edges. Any idea on why I'm only noticing this problem with divided pyrocat MC (A1:20,B1:20)?

Thanks
Chris

The drum is probably not level. This cries for a prewet, but you cannot do it with a 2 bath developer.

PE

In my experience Jobos are not the best way to do two-bath development. Development is quite rapid once the b solution hits and the longer exchange times between chemical baths cause streaking due to uneven development. I dip and dunk in tanks instead or do inversion with a couple of combi-plans - a solution in one, b solution in the other.

Well, there is that too!

PE

Using a drum with its constant agitation is also not recommended for divided development.