Corrupted file - error message

I've included Moonlight Sonata as an example of arpeggios in a music ed book, found an old file yesterday with a harmony line I want to keep.

Got a 'corrupted file' message, I clicked 'ignore' and it opened, no problem.

I also checked the 'Details' when I got the corrupt message, shows a problem with staff 2 starting in measure 22.

There's 3 instruments - piano, mando tab and bass. Mando is staff 2.

In edit>instruments and on the score it shows mando tab, but in staff/part properties it's shown as a Grand Piano.

Piano and bass seem to be fine, mando plays fine all the way through. measure 22 but when I try to copy it, message says 'select the complete tuplet and try again.'

I've tried 'select all' - copies OK but when I paste it says 'tuplets cannot cross barlines'.

Can see in Measure 22 - the last two notes in the mando don't 'line up' the way they probably should - but it's really nice and want to keep it. I tried inserting a measure, repairing and deleting orig #22, didn't help.

I must have copied that line from somewhere years ago, clueless where.

Any suggestions, clues?

Thanks,
DS