Solved Strange artifacts

Hello learned and experienced printers.
I have just successfully printed my best quality print ever but there are strange "gaps" in every layer. What is stranger is that they are all in the same region. I have been noticing these "gaps" in other prints but at random positions around the print but often 50mm after a retraction or layer change.
Now just to make thing really weird I split my tall print in half. The bottom half has the gaps nicely aligned up the middle but the top half has them scattered. I just dropped the print down below the table and went on from there.
I set the start position to always be close to X0 & Y0 to get the joins on the underside of the print.
Retraction is 2.4mm
extra restart is-0.05mm
Retract Speed 50mm/s
Coast 0.2mm
PLA+ 195C Bed 50

Hmmm, what do you think?

Many thanks,
Doug

 

Thanks Geoff.
Don't retraction "gaps" happen immediately after the retraction?
These gaps are about 80mm/3" from the last retraction
Cheers,
Doug

 

Thanks Geof.

Cheers,
Doug