This is bit longer post than usual and is a compilation of a couple different posts glued together; there may be redundant words.
As for quality: any used bushhog (generic term for shredder or brush-hog, not a finish or flail mower) is a risk but careful shopping can cull the dogs. Look for loose U-joints and signs of frequent greasing; look for leaking gearbox. Look for slits gouges holes dings rust-holes in deck and sides and excessively worn skid-shoes along the bottom edges. Walk on the deck for soft or flimsey or flexing steel. Yeah, steel can be patched, but often the remaining is so poor you can't weld it worth a flip, and you still get a distorted patched deck.
If you're wanting a one-time deal, buy new, but be prepared to pay. Same caveats as mentioned. Try to stay away in any case from some of the 'metric' driveline and U-joint sizes and odd (pinched or distorted oddly shaped 6-sided shafts). In your area for new consider Modern: they have a line of hot-dipped galvanized decks that are about the heaviest I've seen. Some of the green line have decks that are dang near 5/16-in thick (they also have some like everybody else that are barn-tin sheet-metal thick). Some of the older blue and red models were hell for stout too.
Once you get custody, contact the manufacturer and wait on them to send you the Owner's Manual for that machine. You'll need to furnish them the Model Number off the tag. If not present they can guess pretty well based on your description. You may need to send them a photo via email.
Some blades can be hard to find in some areas. You said you had two different blade lengths----one's been cut off, ground off, or you have one or both incorrect blades. You need to start fresh with the OEM part number or you'll never get it right. Some blades will have a number stamped on them somewhere if not worn off.
There are literally hundreds of different bushhog blades--make certain you have the correct offset and direction of rotation and mounting hole size---in addition to length.
Locally, I pay about $50 for a set of two blades for a 6-ft Howse.
You might want to go back with new mounting bolts. Make sure the stumpjumper keyway slot is clean and make certain when reinstalling bolts the keyways line up.
Check local pawn shop for large sockets, extension, and break-over bar or buy a bushhog wrench to fit. Use a cheater pipe and penetrating oil. Lube the threads and keyway with thread sealant (pipe dope, not LocTite) when going back together.
After removing the nut the blade bolt will probably be tight. Put the nut back on just to top of bolt and use a piece of wood to punch the bolt loose.
Sharpen blades annually or as needed by removing and using a 4.5-in hand grinder.
Check gearbox and use 85-140-W gear oil or per Howse specs. Some of their gearboxes have a level indicating plug, some don't.
Tighten EVERY nut on the entire implement and go back with new NyLock nuts.
Blades can, do, and will bend and break. First time it happens you'll have a strong desire to be someplace else. Get out of PTO as fast as you can, go back to shop, and install new blade set. Retighten all bolts, again.
Keep those U-joints greased. Replace missing zerks (one each end). Look carefully, may be sheared off.
Depending where you live and the stocking availability in your area you'll probably do better to buy locally.
If this machine is new to you and you're not the original owner my suggestion would be to talk directly with the manufacturer and obtain the blade part number for that machine. And then buy locally if you can.
If you must, order your first set using that mfg part number.
Later, for future sets, you can shop for pricing using the KNOWN good sample blade.
Why you ask? I have seen used shredders with incorrect, torch cut, whittled, backwards, incorect rotation, upside-down, and everything in between blades. If you use what is now on the machine you truly don't know if it's correct for that use or not. I kid you not bushhog blades are magnets for errors. And believe it or not there are hundreds of possible blades to go wrong with.
As mentioned, some blades do have part numbers stamped into them. Most don't or are long gone due to abrasion and wear. And you still don't know if those are the correct blades for that machine.
If you've got a stump-jumper don't even bother trying to pull it. Locate the blade bolt and cut a hole in the deck to allow access. You'll need a 3/4-drive socket or a bushhog socket-wrench-on-a-stick blade wrench. My bolts are 1-7/8-inch. Yours will be different almost certainly. You MIGHT be able to fit a wrench over the lip of the tub-shape stump jumper. Others this forum report bending a wrench to gain access from the bottom.
If your first blade change go back with new special blade bolts, nuts, and lock washers. Clean the keyway on the blade carrier. Grease heavily when installing. Use thread lube on the bolt threads and tighten tight.
Change blades in pairs. Confirm installation per mfgs directions for orientation, direction of rotation, blade angle-up or -down. Spin by hand with blades straight to make sure not hitting deck anywhere. Support the unit if you're under it and DO NOT depend on tractor 3-point to hold it up. Might be easier to stand it up against a tree or stout fence post.
Grease gearbox and U-joints. Tighten 3-point lift pins and entire frame assembly.
Be prepared and keep in mind that blades can do and will bend and break---the first time it happens it'll scare you witless---turn off the PTO, clean the seat, and drive back to the house to replace both blades and retighten everything that shook loose.
Blades can be resharpened. See what new blades are like and duplicate on your blades when they need it. 4-1/2-inch hand angle grinder is just the ticket and can be done on the machine for a touch-up.
Please post back your experiences so we may all learn.
