I replaced the damaged part (TOP227CN) in the HD24 smps ,
its working now again ,
I was able to update the firmware from 1.20 to 1.21 using MidiOX to send the sys-ex file ,
took a little fiddling with the buffer settings and a few failed attempts , but all good in the end .
I tried the BRC , it seems to work ok but pressing rewind to zero caused a minor issue because obviously the tape based adat can go back before 0,00 but the HD24 doesnt ,
The HD24 wont go into record at the 0.00 position , just allowing a few seconds before the song start locate point and thats no longer an issue .
I took a bit of a risk buying the unit faulty , cost me 200 euros , the BRC cost 70 ,
the new IC cost 5 euros ,its still a good deal for a decent 24 track standalone recorder by anyones measure ,so Im happy as a pig in his proverbial muck 
Many thanks also to user 'Spiritworks' .