Sounds like the spirals of the reel are just too close together to get good circulation of the developer. You might try less developer in the tank, so that there's an increased air-space. That might improve the agitation.(posted 8670 days ago)
Two inversions, once per minute, are usually all that's needed with most ss tanks and reels.How bad is the unevenness in the skies?
If it's easily visible, and has fairly sharply defined edges, then it's likely that air pockets are getting trapped between the layers of the film. Another good indication that the spiral is just no d**ned use.