Welcome to the site! :schild27::schild27::schild27:
Sorry to hear you're having problems, but we can get you going again. You can download the service manual for your machine here:
http://www.vmax4.com/vbulletin/showthread.php?4779-Vmax-4-750-Service-manual You will find the answers to a lot of your questions there.
I agree with Kahunas, do not drive it with a cracked or damaged secondary. When you do get it running good, it will probably just explode. Members here will help you with parts, or help you find them. Secondary clutches come up on ebay all the time, there have been a lot of '92 parts on there lately. Your local snowmobile boneyard might have a sled you can get parts from.
The ratcheting is probably the drive cogs slipping on the track. The procedure for adjusting the track tension is in the service manual. You can adjust the chain tension before you take the chaincase apart. There's a bolt and nut sticking out the side of the chaincase about halfway up. Loosten the nut, turn the bolt in until it's finger tight, no tighter, then tighten the nut back up.
Is there a TORS light on the dash when it's bogging? These sleds have a safety mechanism that will restrict the engine RPM if there is a problem with the throttle linkage. If it's hooked up properly, the light on the dash will come on. If your secondary has a hole in it, your belt is probably no good. The service manual also shows how to check the width of the belt.
The front straps on the suspension will keep the front end of the sled on the ground during acceleration. Unless you want to spend all of your time looking up in the sky, you should replace those.
Check some of those things out and let us know what you find.
Shark