Z-motor moves slow

Reprap i2
Repetier Firmware
Arduino Mega / Ramps
Resolution 2560, according to [prusaprinters.org], screw lead
All switches installed (1/16)
Repetier firmware 0.92 was configured with all defaults on their site, except for Resolution 2560:
Resolution 2560
Max travel speed: 2
Home speed: 2
Travel acceleration: 100
Print acceleration: 100

Problem: when I use Repetier Host to move z-axe up/down, it moves REALLY slow and travels 1/20 of the expected distance, i.e. 1/2 mm when I ask for 10 mm.

Any ideas?
Thank you.

Important additions:
1. If I plug Z-motors to X socket, they spin fast. So it is not motor.
2. If I plug X-motor to Z-socket, it does not spin. So it is a socket or soft.
3. If I issue a command M92 Z2560.00, Z-motor moves fast and as expected. So it is not a motor - it is something in Repetier Firmware.
I have attached Repetier's files, could someone comment, please?
As a min., can I incorporate that command into the firmware, so that it is issued at start?

Edited 1 time(s). Last edit at 02/17/2015 01:10AM by Fizpok.

Just a clarification to the second post in this thread. Once I enter M92 Z2560, the Z-axe works fine. Before it, it spins VERY slow.
I am looking either for a reason, so I can fix it, or for a way to issue M92 Z2560 every time I reconnect.
Note: I don't think I can use it as a start code, because then I will not be able to use (at fast Z-speed) the "manual commands" in Repetier host.

What you're doing with M92 is setting the steps_per_unit for the z axis. What are the step settings in your firmware? Because it sounds like your steps for z are too low.

In a firmware steps are 2560. Howevem, steps are just that - steps. They have (in theory, inho) nothing to do with speed. So when i set them in firmware, they affect the angle Z-motor turns, as one would expect.
However, for some reason it turns SLOW.
For some reason, when I set steps from Repetier Host, by M92 Z2560, the speed increases dramatically.
I am looking for a way to do the same in firmware.

Works fine in Sprinter, btw.

Is not the steps, is the feedrate where you're having problems. You need to increase the feedrate in Repetier.

Once you get the right speed, then check the steps to be sure it's moving the correct distance

Have you made any progress on figuring out the problem? I'm also having the same issue - changing the z axis federate in Repetier does not correct it, changing firmware steps does not correct it, but setting the steps by issuing M92 through Repetier Host does.