Mike,
The roller bearing will seem looser than what you might be accustom to since it is a single row and what you may be feeling is the ease with which the plate tips verses pure radial clearance. It probably does has a bit extra radial clearance so that it can easily slide axial as you work the clutch release. Of course, it could also be just clapped out...
You do want to minimize the clearance as the pull of the chain, notwithstanding the bearing directly underneath, does tend to tip the clutch plate, as well as the pressure plate on the flywheel hub, all of which can cause the periphery of the clutch to drag even with the clutch fully released. There is not a lot of clearance for the clutch disk when the pressure plate is fully lifted, and Douglas continued to make changes to the lightweight clutch design all through the 1923-1930 time period.
As mentioned in this thread, you can get new rollers. And that is fine if most of the wear is in the rollers. If the races are worn, and you reground the surfaces, you would need to fit oversize rollers. And those are nigh impossible to get anymore. Certain sizes you can get by reworking (mainly by shortening) oversize rollers for the older Harley-Davidson and Indian v-twins. But I do not recall if 1/4 diameter is one of them. A lot of times the inner race will be stained and the outer may have what looks like chatter marks. I have also seen the sprocket bore warped slightly out of round. If not too bad you might well leave alone, since the lack of oversize rollers negates the ease of re-grinding. Keep in mind, that bearing only momentarily sees action when you lift the clutch. This is why you often see chatter marks, the rollers hammer the sleeve in one place for extended periods.
The other place the clutch can be sloppy is the pressure plate the flywheel hub interface. This is something you can rectify if you have a lathe large enough to swing the flywheel. You can give the pressure plate bore a light hone to true it up (if needed) and then turn the flywheel hub to accept a thin wall bronze sleeve on the outer diameter. Turn this to be a nice sliding fit with the pressure plate.
While the welded clutch disk center is unsightly and poor engineering, I would agree with Eddie and say best to leave it alone and meanwhile look for a better example. Put it on a mandrel and see that the disk runs true to the bore. If it wobbles, then you will have to do something to rectify that.
-Doug
[fix typo. 07Feb16, Doug]