One reason spot lock may be off is because one of your trolling motor batteries may be bad. This happened to me on my 36volt Terrova. It swung back and forth over the spot lock. One battery out of the three was going bad. Solved the problem by replacing the battery. Also It is always a good practice to turn into the wind before you engage spot lock.

I didn't have any expectations of the spot lock holding it in one tight spot. I was never able to control my old tm and be able to hold on top of a brush pile in wind, especially while trying to fish and do other things in the boat. For the fishing that i do, i just need to be in the general area. It works great for that. It appears to have been just a fluke on what it was doing. Maybe the battery didn't get charged properly or just had a bad signal. The system is 12v and the battery is new and in good condition.

I am going to just keep going and if i have any further issues then I will contact minn kota