Sometimes, if the magnetic collar is too high up on the shaft it impedes the rotor's key from locking into the shaft and it spins freely.
The other issue is (if you broke off the tabs to allow the collar to slide down the shaft a bit) you can get the collar too far down on the shaft and it won't line up with the trigger device on the 1146a.
I've been happy with my EI once I worked out the bugs. Just things to think about if you are having trouble.
