Thanks for the replies. Well I never would have thought that plate was original as it looks very bodgy but it seems it must be.
Here is a shot that shows the crushing that has occured on the top side of the guard.
I suppose it should knock out ok.
My Wm20 gearbox bolts did not have any serrated washers but my ZB34 that I am working on has two.
I bought a new front bolt for that but it was too short to fit the washer on so had to source a longer one. There was about 15mm difference in length I think. I'm not sure if they have the same part number but are easily confused. I'll take a photo of the two tomorrow.
I need to make a correction here.
It is the rear gearbox bolt that is too short. The one with the adjuster on it.
There is about 8mm difference in the length of the two bolts. Enough to get a serrated washer on the longer one but not enough on the shorter one.
If you want to use the short one in combination with a serrated washer you could adapt it by taking a few mm of the thick part of the bolt and file the flats a bit further. And take the same of the distance piece so that you have more threads sticking out.
As result you may also have to file the fork which take the adjuster a bit deeper. This brings the adjuster a bit closer to the mudguard but there is usually enough room for it.
But it a bit of a shame to adapt such a nice looking bolt...:slightly_smiling_face: