Panther 440 Not engaging reverse

Hey,
I have a problem with my dad's friend's Panther 440. I took it out for a ride saturday, 10" of light and fresh powder over some really hard ice...( It has been hot and cold all winter long...) So basically, i was having fun, until i had to put it in reverse to turn around and it didn't engage... It makes a weird grinding sound, and when the engine is off, if you pull the lever, and let it go, it makes a metallic sound... I'll take it apart saturday and see the inside, but when i look at the bottom of the chaincase, it seems like something is broken... Could i have broken the chaincase?? If so, i really can't explain myself how...
Any suggestions or thoughts in what could be wrong?

Thanks and cheers

Tiz

any hints?
thanks

thanks for the hint, i tried to pull the fork linkage directly with my hand, disconnecting it from the reverse lever, but it still makes that grinding sound and still doesn't engage...
thanks

Today i took the dropcase apart, and both sides of it are broken... while i was taking it out, i noticed that one of the 3 bolts that hold the bottom bearing was missing. my best guess is that the bolt went flying out of the gears, and hit the dropcase and broke it. The bolt that hold the chain tensioner is also broken and the slip pins and the spring retainer are damaged. Probably due to the bolt coming out too much.
Now i looked at arcticcatpartsnation, and articcatpartshouse, but i can't find the dropcase for the reverse ( ESR) version of the sled... the Drive/Reverse dropcase assembly in the schematics don't include those parts... the only included are the ones for the non reverse version... Where could i get those parts for cheap? Any other hints on what could have broken the dropcase??

Thanks tiz