Nic_s. You give no indication where you are. (someone might suggest a shop nearby if they knew where you are)
I read this thread this morning but needed time to search my box. There it was after more years than I care to remember.
I think it's a Guyatone or something like that. I used it on my old Epiphone 12 string before I had the Fishman fitted.
It's an "el-cheapo" but it still works...(tested it on my Ibanez into the PA) Needs to be held in place with some masking tape or prestik. :-[
Yours if you want it. Just need someone to get it to you.
Seasick Steve - Started out with nothing, and still has most of it left. ?