Stringing - PET left on spool for a long time - thoughts  

Stringing - PET left on spool for a long time - thoughts

I have a a Prusa MK3 - printing PETG ( 1.75 mm ) .

It is over 2 years since I last used the printer and so I am rather rusty in my knowledge. 

The filament has remained on its spool during that time so has most likely become 'wet' from the moisture in the air.

I was reasonably sure I should put a new spool in, but thought I would try everything as it was. Amazingly ( to me anyway ), it seem to pass the various calibration tests, including the 'first layer' test. I started the print,which initially seemed OK, but then I noticed stringing. The print finished and when I tried to remove the print from the model, one of the legs snapped off. I attach 2 pictures, showing (1) at the left a print from over two years ago, at the right the same model printed yesterday and (2) the a close up.

Looking at the close up, one can see 'circular grooves' in the recent print ( at the right of the first picture ).

So I guess my question is, with all the problems associated with moisture and subsequent stringing, would it also explain potential structural weakness that  gave rise to the leg snapping off when the print was removed from the bed ?

Thank you for any thoughts/explanations/advice.

Mike