Perfect pass doesn't seem to work

I've have my perfect pass wakeboard pro on a 2007 sanger v215 for years and never used it. It does not seem to hold speed. I used my buddies over the weekend and it works great. I've read the manuals and YouTube videos multiple times and still can't get it to work right. Should I use the reset feature. It does not seem to be calibrated. If I do this, will it be easy to simple set the speed and use it. And help or step by step directions are much appreciated