Audio delay and echo

I have been working with Cubase 8 for about 5 months and have been having an intermittent problem with delay and echo on audio (vocal and live instrument tracks). I’ve been working on a song for some weeks with little trouble. There are midi drums and organ and 3 audio guitar tracks as well as 3 vocal tracks.

Currently I can’t record any audio tracks without a delay and echo, even with the monitor icon off. I’m sure it’s a track setup problem but can’t get rid of it.

All of the guitars have to use channel 9 of the Tascam 1800, but have separate buses. I’ve tried deactivating the already recorded channels but the problem persists with little improvement. The vocals have separate channels and buses in the Tascam.

Please help!