There are few things that can affect the grinding efficiency.
Make sure the gap between the vessel and the wiper is not more than 1 mm. If it is more than 1 mm, adjust the gap as mentioned above. If you do not add enough water, the stones cannot rotate well, which delays the grinding time.
If you are grinding urad dhal, let the unit run for 5 minutes after you finish adding the dhal. Stop the unit. Scrape around the bottom of the grinding vessel using a plastic or wooden spoon. This will release the dhal stuck in the corner. Then restart the unit and grind as usual. Urad, being slippery in nature, will not grind uniformly unless the above instructions are followed.
If you grind the soaked long grain rice, make sure to add only 1/3 cup of water for each cup of long grain rice. If there is too much water, once the rice grinds to the rava (sooji) consistency, it starts floating and it will not grind to a finer consistency.