On 23/04/2018 10:33, newshound wrote:
On 22/04/2018 12:22, Bert Coules wrote:
I was using my fairly elderly low-end Ferm rotary hammer to do some
heavy-duty chiseling and the tool fell out.Â* When I tried to replace
it, I discovered that the rubber sleeve would no longer pull back.

Removing the sleeve and the small additional grommet-type thing that
sits in front of it didn't leave me any wiser: the shaft of the chuck
still moves in and out, but even at its extreme inward position the
tool doesn't lock.

Looking into the chuck I can see the lengthways raised strips which
guide the tool in, but no visible locking mechanism - which I've
discovered from an online search should be a ball bearing.

Does this mean that the entire chuck has to be replaced?Â* Another
quick search hasn't thrown up a source, but even if it had I suspect
that it might be almost as expensive, and a great deal easier, simply
to replace the whole thing.Â* Am I right?Â* Comparable budget models
seem to be around for £50 or so.

Many thanks.

You normally need to grease these things with moly (or perhaps graphite)
grease. Both of these are notorious for having the oil escape, leaving a
packed residue of solid lubricant that could well gum up the internal
latch mechanism. I would spray liberally with WD40 or soak it in plus
gas or any of the other popular remedies (diesel, automatic transmission
fluid half and half with acetone, etc etc). And "work" it a few times
and then put it back to soak.

I could have added, I have a meeting this afternoon with a man who has a
similar problem at his nuclear power station.