IRLP COS is not operating


I have an issue. If the node is powered down for extended time, I can turn it and the radio on & all works normal. 
After running for some time (sometimes for a couple of hours sometime a couple of days) the node will stop working.
When it fails, the COS light on the board fails to turn on when a signal is received.
I can use the console and log into a noce or the Echo Test. 
The radio will transmit the audi it receives from the internet perfectly
The board will acknowledge the DTMF tones it sees by flashing the DTMF light on the board. 
It will not illuminate the COS light & will not pass the commands on to the internet
It will not pass the voice transmitted into the radio on to the internet. 

I have tried different radios. (Icom & Yeasu) that require different set up on the COS jumper. 
When i watch the pin for the COS while the radio is actively receiving, the icom shows 4.2 volts @ the COS input pin (DB() as well as at the centre pin of the jumper (with the jumper removed) Same with the Yeasu drops to 0.1 Volt at the COS pin when in receive. 
Pin test the wire harness from DB9 to the Header pin OK.
Check by substitution the db9-header pin cable. I have access to an old V3 board and subberd in the harness from it (obviously no audio but it keys the transmitter when announcing IP and Node Activation. 

Myassumption, failed component level repair required on the IRLP board. 

My limited knowledge of how the system works would suggest that this is not a firmware/ software issue.

Any other suggestion gratefully accepted or information on where to send the board for repair if that is available. 

Or  Is there an expedite method available for ordering a replacement board?

Ralph Garnett 
Node 1188

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