Hi,
This is a challenge. Prior to teaching online, I mentored other instructors and served as dept. chair within the public school system. I found that holding group discussions where we shared strategies for improving teaching techniques worked well. Oftentimes however, there are instructors who need to be directly addressed for specific improvement. Again, suggesting strategies and techniques tended to result in better buy in. Are you able to send them to workshops and conferences that highlight those techniques that you wish to enforce? This could also be an option. It's difficult because as instructors, we feel that we specialize in helping others to learn. We often forget that we too, must sometimes become the student.
All the best!
Paula Bordenkecher