Just noticed I started having a slight vibration in head unit on my ultrex, is this a prop issue?

You may need to remove the prop, Check the shaft for weeds or fishing line being wrapped.

Have you banged it into any rocks or stumps lately?

Could be bad contact with the brushes

If your prop isn't damaged or shaft bent then pull the prop and loosen one of the through bolts to see if it's getting water inside. You shouldn't have to remove the bolt only loosen it enough to take pressure of the O ring behind the head of the bolt. If you will deploy the trolling motor while on the trailer and loosen the bottom through bolt you'll know quickly if there's water inside. If so then it falls under warranty if you haven't had it for more than a year. Water inside the motor could be from a bad seal where the motor housing connects to the shaft or a bad O ring seal. Water in the motor could also cause vibration and issues with the brushes. Once enough water gets inside the motor housing the motor won't run but it will still run with just some water inside. A rough surface on the armature where the brushes ride can cause vibration. A good trolling motor repair center can lathe your amateur if needed and solve this problem. Fishing line between the prop and motor wrapped around the shaft could cause the shaft seal to fail and let water in the motor also, so its wise to remove the prop and check for line frequently. If you've noticed any darker colored stains on the aluminum arm of your Ultrex and wondered what's causing it you're getting water in the motor. The stains come from the water rushing up the shaft and out the head when you deploy it. The water brings a greasy residue with it causing the stains when this happens. I hope it's nothing serious and that I've helped you diagnose your problem.

Larry, while you're accurate, some of the possibilities you pose are not highly common in the big picture. Many TM complaints are simple to correct, so starting slow on suggestions is usually a good way to go; it can help to keep it simple for some anglers. Sometimes (depending on the angler in need) it's best not to mention anything complex until capability levels are understood - as such action may not been needed anyway. We should probably wait to hear about the prop or what's under it before we go too far. Sometimes a photo or two can be telling as well, and the info overflow wouldn't have been needed.

I did pull the prop off, it's in good shape. It did have some grass and braid wrapped around it. Cleaned it off and rotated the prop 180 degrees and put back on. Will see hi it does next time out.

have you hit any rocks or stumps harder than just a bump lately?

Probably