Mbox 2 - Digital distortion on output

[BalanceMusic]

A studio that work at on a regular basis is running PT 10.3.10 with an Mbox 2 on a 27" iMac that was purchased in 2013. Using a Focusrite ISA Two going SPDIF into a BLA Black Sparrow into the the Mbox. The set up has work fine, without any issues for about 3 years. Yesterday after a few minutes of recording, the output began to distort with occasional click and pops that got worse as time went on. I tried a number of things to fix it, including rebooting, but the problem eventually came back each time.

My guess is that the Mbox 2 is dying and needs to be replaced, since Pro Tools plays back fine through the computer speakers. I've also read that there have been issues with Mbox 2 and USB 3, but as I mentioned this set up has work fine for about 3 years and very little has changed.

Any thoughts?

Thanks!