As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAIN HYDRAULIC PRESSURE INDICATED ZERO INFLIGHT. HYD CAUTION LIGHT ILLUMINATED ON CLIMBOUT. RETRACTING GEAR WAS NORMAL FOLLOWED APPRORIATE QRH LISTS. AIR RETURN TO MSP. MAINTENANCE FOUND HYDRAULIC PRESSURE INDICATOR DROPPING TO ZERO INTEMITTANTLY REPLACED INDICATOR OPS CHECKS GOOD.