On 06/08/2018 17:29, Bert Coules wrote:
"newshound" wrote:

Are you sure this is not caused by a buildup of dried grease and/or
cementatious matter from drilling? May be worth giving the chuck a
good rinse in solvent, followed by your preferred oil spray. May also
need to poke in the hole with a brush and/or jiggle any SDS bit around
in the chuck to help clear it.

I did try that in a half-hearted sort of way; I'll have another go.Â* But
the fact that the non-locking happened suddenly and that up to then the
twist-and-lock had felt extremely smooth and positive does make me think
that something's broken or possibly misplaced.Â* I believe that one or
more spring-loaded ball bearings are involved, is that right?

Yup, if you look at the shank of the bit you can see where they sit/engage.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/