Traveller Lower Bracket-Locates Rear Bumper Stud

[Chipper]

I have a 1970 Minor Traveller, on which the little corner brackets at the back of the wood frame (described as "Lower Bracket-Locates Rear Bumper Stud" by ESM) have both rotted to the point where the bumper is getting loose (i.e., can be waggled up and down).

This item:

lower-bracket.jpg (44.09 KiB) Viewed 62039 times

Does anyone know if these are replaceable without having to disturb the wood frame?

I've given the coach bolts a good wire brushing and soaking with GT85, in readiness for when I have to try and undo them...