Remove  the bevel blade cartridge and the start of cut arm,  then place a piece of scrap mountboard under the cutter bar and twist the cutter bar by a quarter of a turn so that the vertical blade holder is facing upwards.

Remove the blade cartridge and blade clamping screw and using a 10mm spanner/wrench, remove the nut and dished washer.

Remove the blade holder, being careful not to drop any of the bearing parts from its underside.

Remove any bearing washers left on the slide block (A) and note the position of the spring and how its short (B) and long (C) legs fit into the recess.

Place the new spring in position, ensuring the small leg is placed in the lowest slot as shown. Next, place the bearing components over the hexagon shaft base, ensuring they are clean of any debris or corrosion. If they are dry, lubricate with petroleum jelly (Vaseline), or a good Lithium base grease.

Place a thrust washer in position, then the thrust bearing, then another thrust washer. Finally, lift the long (A) end of the spring just outside of its slot as shown. This will raise the bearing components up slightly.

Position the blade holder onto the shaft at an elevated angle and move it down the shaft, until the screw head on the back of the blade holder picks up the long leg of the spring.

Rotate the blade holder to its normal rest position and push it fully onto the shaft. Check the outer bearing is still located in its recess correctly.

Make sure the bearing components have gone back to their original position and are sitting flat. Check the rotation of the blade holder, replace the dished washer on the shaft so that it is dished upwards as shown.

Tighten the nut only until any side play is removed, do not over tighten as it can damage the bearings.