R Core transformer noise

Last year I bought an R core trafo and to my surprise when last week I connected to the mains to check secondary voltages (unloaded) it did a lot of noise and voltage was not even near the rated spec, in fact the reading was only 11V instead of the 18V or so specified, that was on both secondaries.

DCR is consistent on both primaries and secondaries and there are no signs of shorts. I was about to open it to see if I could find any obvious problems but decided to wait and first hear comments from you guys.

Thanks, Tony