You might put a clamp on amp meter and see what the amp draw actually is. That would determine a bad motor with high amp draw or weak breaker opening at less than rated amp draw.
I had the same issue with the breaker. Put an amp meter on it but found no fault. It turned out to be a bad breaker. It took 3 tries to get the right one from Foretravel. Be specific when identifying the breaker, the resets come on different sides that wont fit what you have unless you get the correct one.
Thanks Barry, FOT told me that is a common problem and that they just replaced the pump I asked if they could be repaired and was told they don't do that. I like your plan better. If it is the pump surely it can be repaired.
Thomas TA-4101 DC Aux Compressor drawing too many amps (http://www.foreforums.com/index.php?topic=10569.0)
HWH Pump Rebuild (http://www.foreforums.com/index.php?topic=13064.0)
Should you need a replacement, much cheaper than Grainger Thomas Compressor TA-4101-DC (12v DC) (http://cfpwarehouse.com/shopsite_sc/store/html/thomas_270025_compressors.html)