I just bought am 89 Bass Tracker Tournament TX. 17ft. It has a Minn Kota Co-Pilot 50 lb thrust. 

shouldn't that move the boat right along? As it is, it won't move the boat at all. Any ideas? 

Is it lowered enough for the blades to be totally under the water? If it's 'skimming' the surface, it won't move the boat.

 

If there's too much weight in the aft, it might lift the bow enough to cause this.

You should be able to cruise up to about 3 mph with that setup.

First thing. Is the prop spinning?

Sounds like the trolling motor may be wore out

Broken drive pin, bad foot pedal, bad motor, weak battery. Hard to diagnose without more info

Start at the source, check to make sure the battery is in proper working order. Check the voltage at the batter, if it's at acceptable voltage check it with the TM on high. If there is an issue check the wiring, if it's good then the TM has an issue and you can narrow down the issue.  But I would start jumping until battery is ruled out. 

29 years of neglect.

Tom

My 55lb moves my 17ft boat pretty well. Definately something wrong with battery or trolling motor. Does the motor changed speeds when the dial is turned ?

I had that model boat in the 90s with a 45lb trust Minn Kota.  It worked very well.  You should be able to troll 3 mph.

Anything electrical you start with the power source (battery) then clean all the connections and switches. Run the motor out of water, it will not hurt it and change speeds listening to the motor run faster and slower. If the motor does't work it needs servicing. Take off the prop and check the shear pin, remove any fishing line wrapped around the shaft, look for leaking seals. Electric motors run by current energizing the armature via carbon brushes. If the armature is black, not shinny copper color, the brushes or armature are worn out. If you don't know what I am talking about take the motor to someone who can repair it.

Tom