The MOCA transmitters might be overdriving the receivers in the modems.
Also, iF additional attenuation in the coax network made the MOCA transmitters output more to over come it or made the modem downstream lower into the modem, the difference between the 2 signals may have grown and is causing more issues.
You may want to try putting MOCA filters on the input of the modem. Newer DOCSIS 3 modems (like the Motorola 6121) have this built in, older ones (like the Motorola 6120) don't. -- If it's important, back it up... twice. Even 99.999% availability isn't enough sometimes.