After much testing I have discovered where the issue is - sometimes when converting docs from pdf then pasting as unformatted text the sequence of the numbering may not always follow on correctly and as the code is looking for the next number sequence this is where the code kept stopping and starting.

I will have to put together another macro to check the unformatted text first as another problem that may occur is if the manual numbering contains commas or spaces etc. instead of periods.