Found the manual online for this particular radar: PRO1000DS_om.pdf

Seems like there are a few things there to support my arguments:
6.0 GENERAL TESTING PROCEDURES
Kustom Signals recommends that the internal test and tuning fork tests, explained below, be
conducted at the beginning and the end of each patrol shift to ensure the accuracy and
functionality of the radar unit. The results of these tests may be recorded in a radar log,
similar to the one found at the end of this manual.

From this I gathered a few potential additional arguments (a few may be redundant):
1) Officer's does not indicate the results of the test. If calibration was meant as test, pass/fail results are not indicated.
2) Officer does not indicate what test was used for ext calibration. Mfg recommends a tuning fork test.
3) Officer does not indicate what test was used to calibrate the radar (moving vs stopped).
4) Officer does not indicate that he verified patrol car odometer speed matched radar speed reading.

Further to 4):
8.2 MAN-MADE INFLUENCES
Various reflections can cause most radar to display incorrect speed readings. These
include shadowing, combined speeds, moving cosine error and fan speed interferences.
Most interferences are momentary and lack supportive audio required for tracking
history.
2. The combined speed effect can occur when the patrol vehicle and the approaching
target are traveling at low speeds, usually below 40 mph, (64 km/h) and at relative
short distances, typically 300 feet (100 meters) or less. The radar sees a strong
reflection from the combined speed signal and uses this as patrol speed. See Section
8.3 for further details.

8.3 GROUND SPEED
True ground speed of the patrol vehicle is required by all moving traffic radar systems
before a target vehicle speed can be accurately computed. If the PRO-1000DS loses
ground speed, the operator can recapture ground speed by placing the unit in and out of
hold using the HOLD switch on the remote control. In addition, the operator can select
the opposite antenna momentarily, then selecting the desired antenna, which may also
help in restoring proper ground speed.
The PRO-1000DS filter system will always look for the strongest signal in the spectrum as
ground speed. If there is a large vehicle traveling in the same direction as the patrol
vehicle, but at a slightly different speed, the radar unit may display the difference in the
patrol and same direction target speed as patrol speed, called patrol speed shadowing.

5) The ground speed read by the radar may have been off due to other vehicles both in front and behind him that could have affected the radar ground speed reading for his vehicle. Again, the officer does not indicate that he verified his speed.

The potential issue with this argument though is what is stated in the initial paragraph of 8.2 regarding consistent audio history, which essentially he indicates on the ticket with "radar speed and clear audible tone was consistent with my observation.".
6.6 MOVING MODE TEST
Verification of speed readings between the patrol vehicle's speedometer and the PRO-
1000DS patrol speed display is another accuracy test that can be performed. These
readings should be the same, or within reasonable limits, allowing for minor speedometer
error.
Speedometer checks should be done on a daily basis. If a discrepancy is found, the radar
unit should be removed from service until the error can be corrected.

6) Officer does not indicate moving mode test was performed. Mfg states speedometer check should be done on a daily basis.

Another argument, although it appears not to hold much weight, is that of operator certification. Officer does not indicate certification or training. But, I've read a number of posts that say this just serves to annoy the judge... I guess I can put it at the bottom of my list.

I'm also at ends whether or not I should subpoena the officer and I think tomorrow is the last day I can do it... unless I request a continuance. Would love to get some additional feedback on this. Am I grasping at straws or is any of this substantial? I still need to check the radar logs to see when it was calibrated.

Thanks again!