Almost dead "A" String above 8th Fred

[Treetopper]

I have a Morgan Monroe MMS3 mando that the "A" string is tinny above the 8th fret. I have tried new strings, new bridge, raising/lowering strings, nothing seems to get rid of this problem, the frets look good and the neck is as straight as most. What the HECK more can I do. Thanks in advance for your help.

Treetopper

[250sc]

Have you used a straight edge to look for high frets?

If not, put the edge of a ruler on the frets to see which of the frets it touches.