Disconnect mower completely from electrical supply. Turn mower upside down. Support at safe working height. Undo the blade securing bolt (anti-clockwise) and remove bolt and blade. Remove the fan unit beneath the blade which is located on its shaft by a spline. This will reveal the pulley around which the drive belt is positioned. Looking down through the five spokes of this pulley you will see 5 screws which hold down a circular plate which has two downward pointing tags locating grooves on the bearing housing underneath it. The shaft with the spline is off centre relevant to the housing in which it sits such that turning the bearing will move the spline part away from the motor pulley thus tightening the belt, usually when turning the bearing housing anti clockwise such that the grooves ride under the locking tags. If the tags on the spring are engaging the grooves in the casting you can only turn it one way, normally the direction in which to tighten anyway. However, by unscrewing the five screws mentioned earlier such that the two spring tags are not engaged with the grooves, you can turn the bearing either way so that you can slacken the drive sufficiently to remove the belt. If removing/replacing belt you will also have to remove the small plastic cover that covers the small pulley on the motor shaft in order to clear the pulley. This cover is held in place with two self tapping screws. Make sure you remove all dirt from the heads as the indent for the screwdriver is not that deep and you will probably find that a Philips point is better than a Pozidrive head as the latter is more pointed and will not seat properly. This is the correct way to remove the belt. Some people have advocated just undoing the motor to give enough slack when replacing a belt, but using my method allows you to reset the tension correctly. It is possible that due to dirt etc you may initially find rotating the bearing housing a tad tight so I suggest that you slacken the five screws enough to disengage the two locking tags so that you can try and move the bearing housing in both directions to free it. The best way to turn it is to insert a suitable sized rod into the hole provided in the bearing casting (make sure it is a good fit) and use one of the spokes of the pulley wheel to bear against it using it like a lever by just turning it. Do not over tighten the belt to the point where undue side pressure occurs which could result in adverse effect on belt life and bearings. Hope this helps.
Nimrod Langridge, October 2011
