Echo after several days

I have a TDM410 card setup in FreePBX with OSLEC echo cancellation. The lines are crystal clear for 3 days or more and then they gradually start to develop an echo. If I just restart Asterisk and Dahdi the echo goes away and the system will work fine for sometimes as long as a week before the echo starts again. This started several versions back and is occurring in the most recent version (6.12.65) I have looked through the forums and while I can find lots of people with echo problems, I can’t find anything about echo developing over time. It isn’t a great burden to restart Asterisk and Dahdi on a regular basis, but I would like to figure out how to fix this. Any thoughts on where I should look?

Hopefully someone else can help u solve this problem with echo. I would just like to add my sympathies and input. I have had such frustration with Analog to VoIP FXO echo that I have vowed to never connect a VoIP system to analog lines again. Its not worth the frustration, money spent on hardware, or time spent troubleshooting. SIP trunks are cheaper than ever, more reliable, and provide an even higher quality audio than your best analog line.