to be quite open with you, not all of them can be saved. It helps to spray PB blaster in there/ on there, and let it soak, it won't work instantly. Being that yours is a older machine, really not sure if it will come off. There are several "tips" and techniques but I'm not saying they will work. Just suggestions, look and see if there is a allen screw holding it on, some pulleys have them, some do not. I would use that PB blaster and shoot it on top, on the sides, underneath..... basically covering that whole thing. You can use a puller, many auto parts stores have some in stock that you can borrow. Make sure you get a new bolt that goes in the shaft or two if you can- one to replace the original from the machine, and the other is to thread up in there before you use the puller- to give it something to press on without ruining your the shaft and bolt hole.
Another is to use a pickle fork or some call it a tie rod separator. You kind of hammer that in there and force the pulley off. I had some zero turns the other day, I used that method to get one off, another I used a wood wedge or triangle block and hammered that up in there, and used a pry bar on another side and the pulley popped off.
I have seen someone drill holes in the pulley and use a different puller and forced it off too.
Measure and take pictures of the pulley before you start, would be a suggestion. It is difficult to measure it while it is on, yes but get a general idea of what size it is, and which side it up and down with it.
Again not all can be saved, there have been a few that I have had to cut off, either with a torch, electric hacksaw/sawzall, or by air powered cut off tool. Let me know if that helps at all, or if I just went to rambling on and on here.
