On my B36(2002) the stainless screws were stuck to the point where the previous owner broke them both off when attempting to replace a damaged clutch. The remaining ends which had broken off more or less flush with the GRP of the cabin top, defied most attempts at removal or to be drilled out,......
With very careful use of a flat file I was able to make a flat area in the otherwise pointed tops of the bolt remnants, then using a centre punch first I was able to get a thin drill down and through each of the two pieces of broken off bolt. The holes were then enlarged with successively larger drills until I was able to knock out the remaining pieces of bolt.
In drilling and knocking out the remains of the two original clutch mounting bolts, the original holes and tapped threads had been damaged such that new bolts alone could not be used. To remedy this situation I made up a mild steel jig with with two holes in it at the right distance apart for the clutch bolts but of a size suitable for taking a rivet nut, and with a third hole to locate a separate bolt. The jig was located onto the cabin top where it was placed alongside the existing clutches, and the third hole for the separate bolt was drilled down through the GRP of the cabin top and into the embedded aluminium plate. This new hole was tapped with a metric thread to suit the bolt I intended to use to hold the jig accurately in place. Once the jig had been secured, I then selected the appropriate drill for the rivet nuts, drilled through each of the two remaining holes in the jig and down through the GRP and into the embedded aluminium plate where the original clutch mounting bolts had been fitted.
With the holes cleaned up and the jig removed, I filled the third hole with gelcoat, then fitted the rivet nuts and finally bolted a new replacement clutch into place.
The new clutch has been in place for one year, and is showing no signs of wanting to move.