(SORTED)Jumpers for extruder microstepping, need help

Story:

Builded prusa mendel machine with wades extruder, everything was working fine, printer was calibrated and so on.
One day i upgraded my extruder to direct drive one, and the problems started.... printing started fine, but after some time extruder stepper motor stopped working.after some time and fiddling with stepper it was working again.
couple days later was trying to make some prints, but switching on printer, there was no connection port.Arduino was fine but as soon as i connected ramps 1.3 (previously builded from kit) connection was lost and port was not showing up in pronterface.
Ordered new ramps 1.4, connected and found that extruder micro stepping jumpers are not installed on my old 1.3 board, tested 1.4 ramps with jumpers fitted and extruder stepper was not moving, removed jumpers and it works, but after some time stepper again stops working.
I'm sure jumpers needs to be installed, i will try to play with steps per mm setting in marlin.
Any help will be appreciated
Thanks

Edited 1 time(s). Last edit at 02/24/2014 04:15PM by didzix.

Did you reset you vref? Or have active cooling on the ramps. If it is shutting down after for running for awhile, that would be thermal shutdown from the driver and the ramps would need cooling.

Thanks for quick respond
Driver is not hot and i have active cooling on the ramps
Just measured vref = 0.5 volts, witch makes 1.25 amps The A4988 driver IC has a maximum current rating of 2 A per coil
I just cant understand why when jumpers are set to 1/16 micro stepping, there is no action from motor, when it is set to full step it is turning.
I have regular 1.8 degree nema 17 steppers, extruder stepper have planetary gearbox with a 5 2/11 :1 ratio.
when extruder motor stalls on the middle of print i can see it still retracts but is not pushing filament thru. Hot end is working perfect.
It feels like there was not enough current coming to stepper. tried altering steps per mm in marlin, but no effect

Edited 1 time(s). Last edit at 02/23/2014 09:35PM by didzix.

tried to adjust pot settings on driver, but no luck.
taked jumpers out and motor is spinning
Do anybody experienced same?? I cant leave it like that, knowing that on half of the print it will stop again...PLEASE NEED Some HELP, advice

Found faulty stepper. taked off gearbox, gear on steppers shaft was loose.If somebody knows any Uk distributor for nema 17 with planetary gearbox, give a shout.THNX