Repeats not working after various edits

This piece used to play perfectly in 0.9.6 r2811. However after various edits, mainly changes of harmony and words, the repeats no longer track correctly.

For example, start playing at bar 17 and the piece plays straight through to bar 18 then to the end rather than repeating from bar 2. The same is true if playing from the top.

I have deleted and re-entered the repeats to no avail.

Operating system is Mac OS X 10.6.3.