Jumbo 3 TX and RX at same time..!!

[bigpimp347]

Radio Make and Model: Jumbo 3
PCB Number: PTBM133
PLL Number: PLL02A

a recent buy for the collection..
RX is fine, 100% spot on..
TX is the funny one..
it seems to RX it's self..
you key up TX meter goes to where it should, signal meter shows 30+ signal being received..
this is AM or FM..no sound heard from the speaker, TX audio is good..

on SSB volume DOWN TX is good on frequency everything, just shows signal in the RX meter..
turn UP the volume and you get feedback, best described as it's hearing it's self..

sure this was a fault i found in a multimode 3, and a simple switching transistor, but can't for the life of me think where or what it was..

any help guys, i paid a lot of dough fo this baby for the collection, so love it to be 100%

thanks...