I'm pretty sure there is not a physical problem, I've had the truck since new, it has 230K mi. on it, and have done all maintenace. I had similar problem with rear seal a few years ago, replaced. Thought had same problem on other side, and everything dry. When had seal problem, ebrake was sticky, not now.
I think I have fluid flow problem, but what do I know, it's still AFU.
I have HCU coming (used), hopefully it'll have residual fluid in all the valves so I don't need DRB cycle bleeding
on it.
Thanks.
Jim.

OBTW, rear not dragging. Awhile back I backed off rear adjustment, better for a day or two. Reverse braking about
10' a day, parking. We've been in house for 13 yrs., familiar with driveway characteristics. Not being smart, just answering questions you had.
Anybody else?