80's marathon jumps to high speed

[cabinfever]

I'm having an issue where the cart jumps to high speed from a dead stop. I put it up on blocks and pressing the pedal half way does nothing. Press pedal to floor and jumps to high. Let off the pedal and low speed will work as long as the wheels are spinning.If the wheels stop spinning, low speed will no longer work.
This has the coil speed controller.

Back story:
I let my mom borrow the cart last summer. she uses it at a campground that has a lot of hills and if she was going up a very steep hill it melted the battery terminal completely off. I replace the battery and upgraded battery cables. the cart would not run. It sat for a few weeks nefore i could get to it. When i returned to mess with it it worked fine. I went back the next week to bring it home and it was running. It ran when i got it home. sat in the garage a week or so then it would not run at all. It sat all winter in the garage amd the batteries were kept charged.

Tested each battery individually they're all good. They are about a year old axcept the one i replaced.

I put a new connector from the key switch to the solenoid and the high speed started working.

[cgtech]

Sounds like the problem is in the speed contacts (most common problem) or resistor coils. The solenoid clicks when the pedal is first pressed right? Following the gas pedal mechanical linkage toward the rear of the cart will lead you to the speed contacts, check them out for burn damage & broken cables. Also check the resistor coils, if you follow the cables from the speed contacts, you will find the coils. The gas pedal linkage connects all the resistor coils inline to activate the slowest speed, and removes coils one-by-one with more gas pedal activation, to allow more current to reach the motor, increasing speed.

[cabinfever]

Yes it clicks.
The cantacts are not burnt and look good. I'll clean them off. How do I actually check the coils? Meter?
Also, I was told by someone the system would need discharged before working on it. I've also been told that it doesn't. Is disconnecting the battery array all that is needed? Everything is original no added capacitors or anything.

[cabinfever]

Cleaned the terminals and wire connectors and runs fine now. Thanks!