How do you do the Churchill Test on a hock?

I had my geldings hocks injected a few months ago. He had atypical symptoms and we went for quite a while not understanding what was wrong. Then I switched vets and one of the things the new vet did was the Churchill Test, which my horse was positive for. Based on that he had a full lameness work up and had his hocks injected which really helped him. But now my horse has been a bit sore in his back lately and I am wondering if he just slipped in our horrible, icy, muddy footing or if his hocks might be bothering him again. So I want to know if his hocks are bothering him without having the vet out quite yet.

The only video I could find of the Churchill test was in Spanish so it was hard for me to understand it.

Anyone out there know how and where on the hock to press?

http://racehorseherbal.net/churchill.html

Did you see this?

There’s also a brief description in this document

https://vetmed-extension.sites.medinfo.ufl.edu/files/2012/03/Passive-Musculoskeletal-Exam_2011.pdf