Numark Matrix 2, CD DJ desk , 2003 ?

The central mixer separate. Anyone happen to know where 2 fibre washers , as used on 1/4 inch jack sockets, would have come from. They dropped on the bench , unnoticed. I cannot see 2 being left over at assembly. The 2 sockets I had left in place so not from there. No obvious place to put them. A fudge due to engineering fixings alignment problem ? In for bad output RCA/phono socket but now in there, the soldering elsewhere is terrible , not PbF probably just not enough solder, ring cracks emerging on the ps board including a wire jumper joint. Bodes ill for the 2 CD units