nu tool electric drill model NPK204c

[DeanThomas]

I have just been given the above secondhand drill , without the manual. Every things works OK except I can't operate the change from the drilling mode to the hammer one, it appears you turn the top collar so that the hammer sign is in line with the arrow, but it wont rotate, Has any body any idea how it works ?. Hope some one can help, Many thanks in advance. Dean.