Another Rev Mod
-You can replace the metal bushing on the main shaft with a bearing used in R/C cars. It's an odd size (6mmx10mm Yoko part number BB-106T-4 teflon sealed 4-pack) so I had to look around for it and I had to buy a pack of 4...no problem, I just put one in each Rev that was still working. Not sure if it really helps but it makes sense and I still haven't changed the Rev on my Intimidator. One thing I have noticed is that now that I shoot really fast (for me...about 8 bps and sometimes 10) I have to make sure I have fresh batteries in my Rev. On some older rev's the bushing that you replace is two pieces...just replace both, the bearing obvious won't fit otherwise.
-In a pinch, you can use an R/C servo to replace your Hopper motor. I used Futaba mini's, they cost about $35.00 a pop unless you have a few lying around. You just have to remove the top third that has all the gears, and use the old servo's gears (hopefully with the bearing mod in it). You'll have to remove the bottom piece that the wires go into (no problem as the same screws hold everything together) on the old servo, unsolder the two wires that are actually connected anywhere, and then resolder them into the new motor and close the servo up. You don't really need to worry about soldering the wires to the wrong terminal...it doesn't really matter if the paddle rotates clockwise or counterclockwise. I've noticed that BE puts inventory control tags on all their stuff now so if you send in the Rev. for warranty work, you might want to put the old servo back in...and hopefully get a replacement and then you'll have a backup motor
-If you have an older, pre-Xboard board, and you notice that the power transistor runs a little hot, you might want to just replace the power transistor with the 15v unit that Philip suggests.
-Weedwacker mod: I went with this mod after I had alot of jams under my impeller (see below comment). I think the Evo impeller would perform the same but my current setup works great so I haven't changed over to the Evo prop yet. I took a stock Rev. impeller (4 blade) and trimmed the blades off with a single sided razor blade so that you have a nub with 4 flat sides. You then drill two holes at right angles to each other, and at different heights so that you can thread two lenths of weedwacker string into each set of holes. Some people drill three holes but mine works just fine with two sets of holes (2 sets of holes = 4 arms). You want to pick the thickest weedwacker string that you can, and pick a drill bit that's slightly smaller than needed for the string. You want to be able to push the string through the holes but you want the holes to be VERY snug. Test the setup for fit in the Rev shell and bend up any arms that touch the shell when you rotate the arms in their path. Now remove the string from the central nub, and install the nub/hub onto the servo and make sure the screw is tight, but not overly tight. now install the weedwacker string and apply a little bit of superglue on the last little bit that goes into the hub just before it goes into place. Don't let the glue drip onto the screw but apply enough to all 4 connections (or 6 if you drilled three sets of holes) to make sure nothing will move. Set the new impeller assembly aside for an hour or two or even better, overnight. Now either shrink some shrink tubing over just the tips or trim the tips so they're not so sharp, and you're ready to rock. Yes, I know the superglue is supposed to harding in seconds, but trust me that more time is more good when you apply it a little thick.
-Bend the Arms mod: It's as simple as bending the stock 4-arm blades up and away from scraping the shell insides. I did it without heat, others use heat. It reduces the overall drag that the motor experiences. Translation: Slightly faster impeller speed and slightly longer battery life, depending on how much the arms were scraping.
If you have several parts laying around (or access to them), you can go through them and test them for speed (the eyes pretty much are all the same as far as speed goes), and pick the pair (board + servo) that works the best/fastest. You'd be surprised at the difference in performance that you see. I know at least one E-gun manufacturer that does this to create an awesome custom gun for special people...and the leftover parts in the bins still make great guns...
One summer I went through three Rev's 'cause I was practicing somewhere hot and humid (8 hrs away) and the balls tended to get soft and would get jammed under my stock impeller. That is when I went with the weedwacker mod and haven't had problems since then.
If you damage your Rev, it's on you. Have fun and I hope these mods work well for you. Let me know if you try it
Ray