check battery voltage,check for welded contact tips [1-A, field weakening]. Also depress speed controller an listen for clicks from two switches. I don't have a repair manual for your forklift. I am telling you this from 38 years of forklift repair experience.
"Anything is possible. You can be told that you have a 90-percent chance or a 50-percent chance or a 1-percent chance, but you have to believe, and you have to fight." -- Lance Armstrong, 21st century cyclist and 6 time Tour de France winner