I had the first maintenance session with my TTSH. It has 80 mini jacks from which 40 are normalled. From these 40 ones three didn't work. I think this is business as usual with ARP 2600. Even the ARP 2600 Service manual explains how you can repair these mini jacks when they fail to conduct from the tip to the shunt. On my TTSH the three failed ones were EXT-CLK IN (internal clock is normalled to S&H clock in), filter input-4 (VCO3 saw is normalled to this input) and VCO1 KBD VC input. I ordered new mini-jaks from Thonk.
Here is a picture of the TTSH 2600 VCF-section where RINGMOD, VCO1-square, VCO2-pulse, VCO3-saw and NOISE are normalled to audio inputs. KBDCV, ADSR and VCO2-sine are normalled to control inputs (a normal is simply a connection which is made to one of the ARP’s input jacks from one of the ARP’s outputs even before a patch cord is plugged into it).