This is actually quite normal. I don't know anyone who doesn't start out pushing and pulling, yanking and tugging on each other when they start Tui Shou.
I'd bet there's not a person on the planet who didn't start out this way.
It takes time for people to realise, and a good teacher to help them do so, that the best method is not to try to outmuscle the other guy.
Some never learn this. Others do so quickly. Most will do so in their own time.
No one can "teach" someone else Tai Chi Chuan. TCC is learned, but you have to learn it through your own effort, it can't be given to you. Someone can guide you in the right direction and in the proper way, but the realizations have to come from inside yourself.
That can't be "taught", not even by the most skilled teacher.
I'm not a "teacher", so my suggestion must be taken with a grain of salt. That cleared up up front, my suggestion is that you subtly guide your students to the proper path for Tui Shou by setting a good example yourself.
When Bill first took on the task of redirecting my misguided zeal at doing Tui Shou in a muscular manner, he worked on getting me to do it correctly, but not by telling me what I was doing (learned from a different lineage) was incorrect so much as by doing it correctly and letting me get offset, a lot.
After a while even the solid rock, which is what I sometimes use for brains, began to realize that what I was doing wasn't working, and never was going to work. After that I opened up and began to follow his lead and actually listened to what he had to say on the matter. I got better pretty quickly after that.
I'm still hopelessly bad when it comes to Tui Shou, but at least I'm not thrashing around violently anymore, simply trying to outmuscle my partner. I've learned that it's better to listen, follow, stick, adhere and let the other guy do all the work. It's much less tiring that way, at the very least.
I've got a long, long, long way to go before I'm any good at Tui Shou, but at least I'm on the right path to get there in the end.
That's all I got. Hope it helps.