How to fix a light thingy??

Hi everyone
I'm a new member. I have gained lot's of helpful info through old threads, a really useful forum. As you can see my technical terminology isn't its best but bare with me!
I have a 50's commission house. The lights hang down through the ceiling and the cord goes through a thingy (a flat, round disc) that is attached to the ceiling. In two rooms the disc has come adrift slightly and I am wondering how to fix this. I looked above the ceiling and couldn't find any bolts or anything to adjust. Can anyone help me with how to fix, or goods ideas of how and what to replace with.
Also a lighting question, although I might try the light forum, with fluro bulbs do they work okay if you attach a dimmer switch?
Cheers
Mcblurter

Is it a plaster moulding, or something else? Maybe a pic would help if you can.

That was quick!!
Not sure if plaster or wood. Will try and get a pic tonight. Have seen similar things in other houses but much more ornate plaster moulds with flowers etc
Cheers
Mcblurter

Back in the 50s standard practice was to have a noggin behind the plate. where the wire came through, or the wire would come through a hole drilled though the joist. That would be why you can't see any fixings.

If it is a wooden disc (I suspect it will be), pre drill a hole so you don't split it and screw it to the joist or noggin. Counter sink the screw head and patch over.

cheers
Rod

Actually it was next to a joist. I might run a thin bit of wood in between ceiling and thingy see if I can locate an existing screw as I wouldn't want this to interfere with new one.
Might have to get the vacuum cleaner in there and remove many years of dust and crap.
Thanks for the info, I'll let you know how I go.
Cheers
Mcblurter

Mcblurter,
Light thingy = ceiling rose.;)
I'm not too up on the whys and wherefores but I'm pretty sure that if you just wire a fluro straight into a standard dimmer than it won't work. Apparently it is possible to dim a fluro, but it's a bit more complicated.

Mick

hmmm, the flat round disc bit threw me there I was thinking of the wooden round plates they used to use to mount the light fitting on!!!!

But yes it may well be a ceiling rose.

Is it made out of plaster Mcblurter?

Could you post a picture so we can give you a better idea of how to fix it?

Rod