-If you have an umbrella frame that works well, but the snap/swivel or other hardware is sub standard, you can easily change it out to more appropriate ones. A round nose or bailing pliers are nice, but needle nose will work. (check out spinner making videos)
-If you aren't getting bit on the center/trailing bait (and the lower baits), it probably isn't running correctly, it may be getting pushed to the side, or more likely in your case, spinning excessively, (umbrellas shouldn't spin).
-Umbrella size should be matched to bait size, within reason, large umbrella/small baits and small umbrellas/big baits tend to create some issues. I know it sounds a like like trolling, but let out some line and watch the rig while running the boat at idle and see how it is running, this will give good guidance on how fast/slow to retrieve as well.