I’ve been having issues going into the first gear sometimes, usually when I’m coming to a stop and I try to downshift and go into 1st from 2nd it won’t allow me or make a grinding noise. When the car isn’t moving it’s not an issue, only when the car is rolling.

 

Then don't do that... simply wait until you come to a complete stop to put the transmission in first gear.

 

Thanks, I figured out the problem which was in my slave cylinder that had a worn out push rod.