I also have an MX-5 on a 3320 with 300CX loader to balance things out, and have no problems at all. It does 'lug down' a bit when I first turn on the PTO, but I've learned to cycle it on/off/on during startup, and it works very cleanly now. Cuts the grass/brush very well, maneuvers well, and does not seem to be "too much" for the tractor.
I *did* have to learn the hard way that you can't mow at a 90 degree angle down the terracing... I bent the metal braces when the tractor hit the level ground, the pivot on the 3PH maxed-out it's travel, and the MX-5 was still trying to keep the tractor's back wheels off the ground. Let's see... 2 four foot long, 1/4 inch wide pieces of steel (even painted green) versus a 2,900 lb tractor and 900 lb FEL -- no contest. But of course this has nothing to do with the tractor/cutter combo -- more with the tractor/idiot-operating-it combo!
Anyone know the best way to straighten out those braces? I'm assuming I could just lay them flat on the ground and "tap gently" with a rubber mallet until I work the kinks out...
I'll betcha those braces are at least 3/8" thick. If you've got a torch, you might be better served to heat them before you try to straighten them out.
Even a small propane torch (used to solder copper pipe, etc.) would help to coax those braces back into shape.
If you don't want to chip up your garage floor, a flat steel plate is a good surface to pound on or I've even used some scab 2x6's, etc. Sometimes I've broken up 2-3 pieces of wood before I'm done but it's better than making a mess of the concrete floor.
A small 2-3 lb sledge hammer will get you there faster than a rubber mallet and help with the small "tweaking" increments that you just "need" to finish!
And you'll get to drop into your local JD dealer and buy a spray can of JD "green"!
Another 3320/MX5 combo here, no problem at all with blackberries, hawthorne, you name it. I always drop the RPMs to ~1500 before engaging the rear PTO, then ramp up to full PTO RPMs. If I engage at full PTO RPMs, it's not as smooth starting up.