Did the OP check with Sports Chalet as to whether or not they keep their TM-1 calibrated?
Do they have a calibration rod or wheel to check against?
Suggestion for the OP. If and when you do get a TM-1, do not even touch it until you have a calibration rod or wheel ready before hand and THEN record your first readings on several spokes or the rod.
This way you can return the TM-1 to it's original state when it does go out of calibration. This assumes of course that the TM-1 comes out of the box properly calibrated and has not been manhandled between PARK - the distributor - and YOU the customer.
I've encountered at least 2 that came out of their box off to begin with.
Do some finishing touch up on your wheels - have another wheel builder with a high grade tension meter and calibration rod give you a second opinion.
=8-)
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5000+ wheels built since 1984...
Disclaimer:
1. I do not claim to be an expert in bicycle mechanics despite my experience.
2. I like anyone will comment in other areas.
3. I do not own the preexisting concepts of DISH and ERD.
4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
5. My all time favorite book is:
Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life