I had one of those 3HP when I got my first jon boat it came with it. That was a great motor. Still wish I had it but the magnets came loose and I didn't know ow how to fix it at the time.
All the motors they sold back then that had the 'Maximizer' circuit built in were the way to go. I've been hoarding and rebuilding them for years. Most of the 3hp motors I find now are extra long shafts but I've started to cut those down to a short shaft. I did save a few in case I ever find a deal on a small pontoon boat but that's not likely around here.
Around my way everyone killed them in saltwater.
If you look at the later years of that design they made the Riptide RT3.1 which was pretty much the same motor but with a carbon fiber shaft and epoxy bedded circuit board.
Most modern trolling motors use a separate set of windings to create different speeds.
The Maximizer was a 'pulse' control type system were rather than burning off the excess power to slow the motor down through a series of resistors it used a transistor circuit to turn the power on and off at full voltage as needed to turn the motor at the requested speed.
The magnets coming unglued were all that ever went wrong with those motors. I completely destroyed my first one not realizing what was going on. The thing started to draw more current and I kept going till it wouldn't move anymore. The result was a can full of magnetic dust and a shredded armature. They were still fairly common back then and I bought a used one, the magnets were still in place on that one so i turned a wood plug to fit on the brush side of the motor which I could use to position the magnets with, I then worked the magnets loose, sanded off all the original glue, and reattached them with JB Weld using the wooden jig I made. I've since redone over 200 of them but haven't run into one in a while lately but I've got a few more to redo if I ever get around to it including a 4hp/24v model in all chrome for an anniversary edition.
A lot of people scrapped their older trolling motors because parts were always outrageously expensive and nearly non existent through Minn Kota but if you have a good automotive electric dealer or rebuilder a good bit of that motor comes from a similar starter motor The armatures can be rewound if a good used one can't be found, brushes can be matched up from a generic assortment and the rest us basic electronics.
Years ago someone gave me an all stainless steel trolling motor, it was branded 'Old Pal'. The motor and controls were cooked and had filled with water and were pretty much destroyed but the bracket and shaft were built to be indestructible.
I gutted the control head and using two smaller Minn Kota 35lb thrust motor units on a two into one adapter I welded up, I mounted both side by side on the stainless shaft running two of the early style Lexan type props.
I then copied the Maximizer circuit from the 4hp and ran the two motors off a pulse control circuit at 24v.
After the first test run I realized it was too hard to steer with the foot long tiller handle. At first I just made a longer tiller but that wasn't much better so I went to a stick steer and cable that gave me more leverage over the two motors. I thought about running the one motor in reverse but there's no reverse prop options made for a trolling motor and having one made would be too expensive.
Power wise it was brutal. Part of the issue I was having was that the two motors were flexing the shaft and creating binding in the pivot bushings on the stainless mount and shaft. I added two Torrington bearings to the thing that helped but they were never going to last being wet all the time despite heavy grease.
I eventually converted it back to one motor and ran that unit on a 12ft glass runabout at 12v as more of a toy.
I gave the set up to an elderly neighbor for her pedal boat a few years ago.
