I found that the wind-face of my Transair TPS-1 gave the wrong results. Several of my answers were a degree or two out from the correct answer - which really didn't help at all.
I assumed it was ham-fistedness on my part, so I had my instructor check my use of the whizz-wheel after the exam and although I was spot on, the TPS-1 wasn't. I suppose it
could just be mine that has a problem.