I made it down 4 steps, and my crank arms are as twisted as my ankle. HELP/advice?

Made 3 steps last night, tried four today. Ouch.
My ankle will heal, nothing too bad there.
the crank arm is twisted, and the cotter pins have losened and are slipping a lot, even though I’ve been been hammering them in every day or so. My ankle is hurt because I slipped off the pedal because the arm bent.
I don’t get it.
I just got these new crank arms last week. The pins I got from uni.com didn’t work at all–they were too small, but the old pins still worked fine. I hammered them in, and they were loose again within a day or so.
I keep having to hammer them in–I’m I’m hammering them in hard, pounding them like a sweedish supermodel, and they keep getting loose–except that now, they pretty much flush with the crank, so I can’t hammer them in any further.
So, I guess it’s time for some major upgrades. My uni is an old schwinn 24", with a new KH saddle, seat post, and tire.
I obviously need new cranks, but I’m done with cotter pins. I’m only doing drops of about 6 to 10 inches right now, but I’d like to get better. I hear lots of complaints about cotterless cranks slipping, but splined are really expensive.
I was thinking about getting the uni.com hub ( http://unicycle.com/shopping/shopexd.asp?id=738 ) for my uni–anyone know if that will fit on it? Then latter on down the road, I’d change the rim to a 36 spoke rim.

Or would it be a lot better to go for a KH hub with KH crank arms? I don’t really know if I can afford that, but it it really is much better, I might do it. It seems like it’s probably overkill for what I’m doing - hopping down stairs and over things. I weigh about 150 lbs.

I know I should really probably buy a new unicycle instead, but unfortunatley, that would basically mean not unicycling for several months until I got enough money to do that.

EDIT: sorry about the repeat posts–my internet connection (public computer, sucks) kept telling me it wasn’t working…

I will keep this version in the forum and trash the others.

For the time being, you could try getting some bigger cotter pins until you can afford a replacement for your antique system. Try Tommy Miller at The Unicycle Factory. He doesn’t use a computer so you have to call him: 765-452-2692. He probably has tons of exactly the right size pins to help an aging Schwinn.

If no pins work, it may be because you’ve worn down the notch in your axle. In any case, you need to replace your crankset. The Uni.com axle is a good upgrade for cotterless, but obviously you will get much longer life from a splined design. I’d recommend starting to save up, because your Schwinn has other limitations besides a failing axle. Replacing the axle will mean replacing the entire wheel, as you won’t want to continue with 28 spokes and an oddball rim size (1 3/4"). Just start with a new machine. You can always keep the old one as a spare, and to use for teaching your friends.