thank you Heywood! I did think that might be the cap but was unsure. I posted the question, took the dog for a walk and came back to find this extremely helpful answer and more!
I may not have to get a manual now that I found you! Actually yes I want to download one from trade-it but I need a better internet connection before I do. I originally thought I might have to replace the belleville spring in the forward clutch, but yesterday as I was checking fluids I discovered the shuttle was at least 2 quarts low, I've been adding to it slowly and checking like you described, and it's now at least showing on the dipstick. I think the previous owner was checking it when warm, but not running because that did indicate on the dipstick. I'm hoping that solves the issue of it slowing down in forward when warm.