What was found
FL 350 .76 MACH `A` ENGAGED, LNAV/VNAV, FMC SOURCE SWITCH BOTH ON R DUE TO MEL 34-36J. RIGHT FMC SUBSEQUENTLY MOMENTARILY FAILED. VTK FLAGS ON BOTH MAP DISPLAY AND FMC, P/RST LIGHT ILLUMINATED, A/C REVERTED TO EWS AND ALT HOLD. A/P `A` REMAINED ENGAGED. MALFUNCTION SELF-CLEARED PRIOR TO QRH ACCOMPLISHED. GROUNDED - YES. REMOVED AND REPLACED #2 FMC COMPUTER PER B737-900 AMM 34-61-02-400-801. FMC OPS CHECK GOOD.