Requesting basic Gibson LG- repair/maintenance opinions

[John Arnold]

I think I see old lines where ladder braces were?

Correct. LG-0 is ladder braced from the factory.

Is/was it common to x-brace OVER a bridge plate? I am a newb by this boards standard, but I've never seen that.

Martin tucked bridgeplates until around 1947. These were just under the X-braces about 1/8", with a rabbet cut in the braces to accomodate the plate. The finger braces and tone bars were tucked in a similar manner. On the guitars I have built using this construction, I would glue the bridgeplate, finger braces and tone bars first, followed by the X-braces. This is opposite from the sequence I normally use. The rabbets in the X-braces were carefully fitted so that there were no gaps. While it secures everything better than butting them together, it does make bridgeplate replacement a chore. It is the main reason that a replaced bridgeplate on an older Martin usually decreases the value. It is a job that has often been poorly done.