Bottom line on reinstalling the Rev. chaincase cover for the first time.
"it was easy, it slid right on!" ----- You did it wrong and didn't properly seat the fork.
Once you do it a few times youll get the feel for it. If you can get you head close enough you can sometimes look from above and see the fork just before it reaches the groove. Another trick is to work the conecting arms before you bolt them back to the Rev. lever. The lever gives you more leverage (imagine that) which can make it difficult to feel that you're moving the gear against the spring.