abs fault code #32 any solutions

Keep getting ABD green light coming on and heavy vibration in the right rear wheel for the first 20 seconds of driving.  Then Red abs light and yellow traction control light come on and problem goes away until I turn car off then happens again.  Have an experienced Porsche trained mechanic working on the problem.  He says its a Porsche Fault #32 (front right valve in the abs).  Tried the brake flush and brake flush with DOT 3 which eliminated the feedback on the brake pedel but the ABD keeps coming on.  

Any suggestions on a fix without replacing the abs unit would be appreciated.  If replacement is only option does anyone know if someone rebuilds/swaps abs units for the 95 993.

Thanks in advance for any suggestions.

Matt Selner