Sorry, craigh, I didn't know you'd moved the thread. See, we're all still learning.
Okay, so if you unplug the amp from the wall and use a multimetere to measure resistance between the two prongs of the wall plug, you should see low resistance (< 100 Ohms?) If not, then the fuse is bad, a wire is broken, or TubeDriver is right and the primary is open so the power transformer should be replaced.
There is a section on troubleshooting in the kit manual, and it shows pictures under the chassis. Take a look and maybe the fix is easy! It's usually good to have the unit working before modifying it so you can assume any problems are caused by the new modifications.
Go to <http://www.dynaco-doctor.com/st7_mnl.pdf> to download the manual (look around this site, too, for information.) The troubleshooting section starts on page 9 (Page 13 of the PDF.)
www.dynaco-doctor.com Also has a repair guide from Curcio - take a look!
If your amp is stock, there is also a selenium rectifier in the bias-voltage circuit. This should be replaced with a solid-state diode like the 1N4007. Selenium is nasty.
Maybe after you unhide the amp, we can arrange a place to get together and test a couple things if you don't have a multimeter and such. I'm in Howard County, MD (pronounced How-Weird) so that may be close to you?