After meridian flip, auto center on target is very slow

Hi
Before meridian flip, auto center on target is very fast like 2/3 plate solve and slew from 2500pix error to 10 pix error.
After meridian flip auto center on target is very slow like 8/10 slew 5 pix by 5 pix to ritch target.
German mount is under Ascom Eqmod pulse guide with RC tube 10’ focal 1500 mm. CCD bin2.
All soft are updated.
Something wrong in SGP or Ascom parameter ?
One way to help me ?
Thank you for help

Régis