Assuming you've excluded the possibility of camera light leaks etc, you're describing insufficient agitation.(posted 8950 days ago)Use a double-size tank, load one reel with film and put it on the bottom, and put an empty spacer reel on top of it. Use just enough solution to cover the bottom reel.
When you pour the developer in, bang the tank a couple of times, then invert continously for 30 seconds. For the remainder of the development time, invert the tank two or three times during five seconds every 30 seconds.
You can fit 1 120 reel in a 32-oz tank or 3 120 reels in a 64-oz tank. _Never_ completely fill the tank.
The result will be very evenly-developed film.