I have one as well, mine is a HR8, about a 5 ft cut. I have had to buy some small parts over the years and they don't seam like they are a problem to order. My parts came from a local tractor dealers. Prices weren't to bad. Many dealers seam to carry them, sell them special order, parts the same way. Mine has been a work horse. Have gone through 2 sets of tines, on the third set. If you can get it at a good price, snap it up, you won't regret it. I found mine in a brush pile overgrown where the owner had passed away. Paid $100, cleaned it off and ran it. Only caution I have to pass on is make sure you adjust the slip clutch yearly, this is a safety item, The manuals are available as a part and the procedure for setting the clutch is in the manual. You need this thing to slip if something gets tied up in it.
Chris