Can't get high RPM's

Just had 15 yr old Honda Harmony 2 mower serviced with new carb installed. Prior to service, the mower would start fine after 2-3 pulls with choke engaged. I would let motor warm up and the pull throttle back to fast mode but could never get the higher RPM's it had previous season. It has enough RPM's to drive but never gets to the RPM level it had when new. The new carb made no improvement to the throttle control. I tried to make an adjustment to governor arm on the shaft thinking that might solve my problem but it only resulted in the motor running at very high RPM's with no throttle control so i set it back to original position. Could the internal governor mechanism be worn out out or is there some other exterior engine adjustment I can make that will give me more throttle control for higher range RPM's - THANKS

The throttle set the maximum amount the engine can run at.
The govenor slows down the engine.
So your govenor is working.
Set the throttle control to full speed.
loosen the cable clamp and pull it back till the throttle lever just kisses the choke lever without moving it.