Hey.
So it sounds like the problem is related to the red switch block on the side on the tb6600. They control the microstep modes and have to be in synch with the settings in grbl.
For example if you have a 200 steps per rotation stepper and a 2mm pitch leadscrew then it would mean that for every 200 steps sent, the screw will turn once. If you have SW1,2,3 turned to "off" then youll be in 32 microsetp mode. This means that every 200 step pulses you send will only cause the stepper to move an equivalent of 6.25 steps (vs full stepp or non-microstep mode).
Check out those switches first and see what you can see. If you want to keep running at 32nd microstep then youll have to factor the base motor value with the driver microstep value: 200 * 32 = 6400 steps per full rotation