posted 12 years ago
By "mechanism that engages the chain" do you mean the chain tensioner?? .s opposed to the drive sprocket/clutch.
If yes, then you likely have to adjust the chain tensioner to the "looser" direction, allowing the bar and chain and cover to line up appropriately. At this point the chain should be sloppy loose on the bar.
Once you get all the various bits to fit into the appropriate slots, the cover will slip right on there. Then mostly tighten the two nuts that hold the cover on. Then remove most of the slack in the chain. Give the final tighten to the nuts and you're back in business.
Post pics if this doesn't get you up and running.
troy