New balance is broken

Hi, I spoke w a representative from your Company last week and we identified the parts I needed to replace on my window, new channel balances S350-36 (3550). They arrived and I followed your video instructions on how to remove the old ones. I then followed the instructions on how to install the new ones, however the left one did not catch as it should have when I attempted to slide the window down in place and suddenly the brand new right one I'd just installed sprung up full force and the plastic piece cracked right off! I'm so frustrated. I tried installing one of the old ones in its place (the better of the 2) but now, though the new one on the is catching fine, the right one is still sticking up by about 2 inches. Please advise.

Ok, can you tell me what kind of sash guides I need for this kind of channel balance that I ordered? And once I get the sash guides on will it work in the condition that that the old one is in? I'm so frustrated because I just spent $25 on 2 brand new channel balances from you guys and just as I was installing them the one on the right flew up and broke (the plastic piece at the top came right off as you can see in the photo) so now I'm left with one new and one old that's got a plastic piece chipped off.