I just bought a corded hammer drill from Homebase, brand PBX (their
own) and,... I cannot work out how to insert the drill bit. (Pause
while you all have complete hysterics) It's a keyless chuck where you
pull the rear sleeve of chuck back and then turn front sleeve to
tighten/loosen the chuck.

The rear sleeve seems to move back, although only slightly and the
front sleeve only turns a half - 3/4 turn which barely tightens the
chuck at all.

I know this is absolutely stupid but I am completely baffled and
embarassed to have to ask for help.

Please someone put me out of my misery!