Yaesu GS232B and G5500 did calibration in manual, all is OK. 180 and 450

Using Satpc32 with Yaesu Gs-232 rotor interface selected. Settings 2-60-N-0 selected as options...... Stored. Quit and restarted program. Go to Rotor control and manually set elevation to 90 degrees and azimuth to 90 degrees. Execute settings. Results are about 12 degrees low. Used the correction buttons to bring up the rotor directions to 90 degrees and saved the corrected values. Quit and restarted program. Back to rotor control, and send rotor to Park position (both set to 0 degrees park position) Both the elevation and azimuth go to about 12 degrees - not zero. Try to correct values by zeroing, save and quit. restart and send back to 90 degrees again result in low readings. What am I missing? Thanks Don.