Smudge ...
Regarding your 'Challenge' ... I'm afraid you have beaten me on the ID of the Woodvale taxiing accident circa the 80's
The closest I could get was the incident with WB697 in 94 when the airframe was airlifted (suspended under) by a Puma back to Woodvale ... see following URL.
Aviation Safety Network > ASN Aviation Safety WikiBase > ASN Aviation Safety Database results
I'm assuming you know the Serial Number in question ... and await your announcement
You'll also see I've added four more airframes to the 6 AEF Fleet List ... these were the final aircraft to serve at the close of Chipmunk Ops at Benson in 95.
Mandator has kindly posted the mod list you asked for ... which covers the Wing Spar mod.
Finally, the Tow Hook mod was, I believe, for Inter-Service & National Gliding ops ... I don't believe (I may be wrong) Air Cadets undertook aerotow ops.
Best ...
Coff.