The indicator check is a fairly reliable check, within limitations, of the bed condition.
There are 2 variations that I perform when I'm checking a lathe out, neither of which require bed leveling.
The first is to place an DTI on the carriage and indicate the inside flat way,
the second is to place an indicator on the tailstock and indicate the inside face of the front V way.
Variations over .004" are cause for concern, IMO, and then I really start checking the inside face of the front V way.
SB's are real bad about wear on that face, as indicated by the ridge formed on top of the V way of a lot SB's I've inspected.
The big problem with excessive wear on the inside face, is transverse movement of the saddle away from the cut,
don't forget you've also got wear on the carriage slides adding to the movement.
Harry
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It's been my experience that if you are showing say .010 wear on your bed ways you will see three to four times that much under the saddle. If you lift the saddle off the bed and take a look you may find that there is a small vertical wall on the outside edges of the V ways. The height of this little wall is the amount of wear on the saddle ways. I have seen these as much as .050 high meaning there was .050 of wear on the saddle ways. So much so that were the saddle bridges over the tail stock V way it was beginning to rub on the top of the tail stock way.

As to an easy repair no there is none. It means having the bed ground or machined as I do on short beds and then machining the saddle and installing a way strip filler to build the saddle back up to the correct height so the lead screw will be in the correct location for the apron and its half nuts. A daunting task for a beginner. My suggestion is finding a better bed and saddle or a better lathe. Be advised if you do find a better bed its very important that you get its mating saddle.
Dennis Turk
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