Hi Anthony, 

Firstly, what is wrong with the jack? Maybe it doesn't need replacing. 

I don't have experience replacing that particular jack, but here is some
general advice: 

 	* Don't try to look for a PCB-mounted part which matches the
footprint. Just forget it! Put in a panel-mounted jack and use hookup
wires between that and the PCB.
 	* Check this schematic:
http://www.kylheku.com/mp1-files/mp1-schematics/ADA-MP1-007-027-jacks.jpg.
[1]As you can see, this is is a stereo jack with 6 terminals: three for
the jack itself, and three for a SPDT switch which is in one position
when nothing is plugged in and the other position when there is a plug.
 	* Although it's a stereo jack, note that the ring connection is not
used; the diagram just shows the ring connection as being connected to
the switching assembly mechanically, but it has no electronic
connection. THEREFORE, A MONO JACK (TIP-SLEEVE) WITH A SPDT SWITCH (5
TERMINALS IN TOTAL) WOULD WORK IN THIS APPLICATION. The SPDT switch
controls which source feeds the return. When nothing is plugged in, the
switch connects the return circuit directly to the send circuit
(bypassing the loop's send and return buffering and level control
op-amps). When the plug is inserted, the switch connects the return to
the output of the return op-amp.

Check out this puppy: [2] stereo jack, with two SPDT switches: 9 pins!
You'd just use five of these connections. Can't vouch for its audio
quality though. Both switches could be wired in parallel to provide
redundancy, I suppose. 

On 11.01.2014 08:22, anthony.i.lee wrote: 

> Do you know what effects return jack for the ADA MP1
> what is it & where can I get one
> Thanks 
> 
> Anthony Lee
> Israel
 

Links:
------
[1]
http://www.kylheku.com/mp1-files/mp1-schematics/ADA-MP1-007-027-jacks.jpg
[2] http://www.mroelectronics.com/mro/product.php?id_product=3600