Aloha Manjusri,
When Master Lin cues you to slightly bend your knees at the beginning of the active exercises, you'll continue that throughout.
There maybe some in-between movements where there may be a straightening of the knee area, but it's not something to get into your head about. Just relax, have the slight bend from the beginning and then focus on the experience at hand.
If a locking of the knees shows up for your during the work, thank it, release it, and continue the work.
Much Love and enjoy the work and weekend,
Shawn
