Welcome to the site! Thanks for joining! There is a good bolens crowd here who can help you out. I dont know much about them and unfortunately can't be of any assistance. Again, thanks for signing up and if possible, everybody loves pics!
welcome to the sight Rachel11 you are the right these are smart when it comes to bolens and they will be more than to help figure out your problem, reallyneed pics and a few more details if possible .
If the H16 is like the rest of the tubeframes, there should be 3 bolts that hold the pto assembly to the back of the front axle. Loosen the 3 bolts and move the pto assembly up, then re-tighten the bolts. This should allow the belts to slip when you turn the pto off.
This happened to me the other day and a quick adjustment solved the problem after I moved the pto down a little to help the ujoint to my mower deck clear the linkage. This tightened the pto belt and it would not disengage. Moving it back up resolved it.
I had this issue with my transmission belt on my massey. The belt was so wore on the sides, that it was riding deep within the v of the pully. Even though the belt was old and strectched you would have thought it would disengage when turned off but since it was wore it was droping into the pully and grabbing thus not allowing the transmission to stop so I could switch gears. I bought a new belt and all was fine after. Check your belts to make sure they are not worn down. You might have the same type issue with your pto drive belts. Just my thoughts.