Loose focusing ring on DR Summicron 5cm F2

[marduk]

Hi,
I have received my Leica M3 with late DR Summicron 5cm F2. The lens seems to have a defect. The focusing ring sits loosely sometimes. It is OK as long as you rotate the focusing ring very gently. But if you start rotating it quicker, something clicks (often near infinity or in between 1.2-1.5m) and then focusing ring sits loosely (sorry for my bad English; can't find a better phrasing). There is about 1.5mm gap. If I do not use the camera for a while it sits tight again.
Do you think it would be easy to repair?

 

[marduk]

OK, there is not this effect anymore, just a little gap. It is caused by factory oil that dried out, so the lens needs a little oiling.