Make sure you put the locking screw in for the cable before you attach the Fan etc.
Also use a 17mm wrench on the crank shaft through the inspection hole at the front of the engine to turn the engine when pushing the Tach drive into the engine.This will allow the drive to move into the engine by not fighting the the worm-screw.If you don't do this it's very difficult to get the tach drive in and you can damage it.Lightly tapping it with a Rubber mallet/rawhide mallet and turning the engine makes it easy.
Don't over-tighten the small M6 bolts.They are only supposed to have between 6/9 ftlbs torque.I use the knuckle of my wrench and socket and make them hard-hand tight.By not using the arm it's very hard to over-tighten them.
Put some grease inside the Fan before slipping it onto the shaft to make it easy to remove in future but use a bit of thread lock on the locking bolt.Again don;t over-tighten the fan locking bolt.
HTH
