[Radioroslyn]

Thanks so much for your inputs. Sounds like I ought to pull the coil and have a look at it after I swap the tubes.  Here again,  I am confused as to what the green dots mean , that you refer to.  
walt

If you can see any green areas on the copper wire on the coil it's a good bet that it will be open or intermittent. Most of the time it's on the smaller outer winding. Has to do with a reaction with the wire and it's insulating materials causing it the rot.