[Boatanchors] Drake TR-7 Xmit Question

[w0ng at comcast.net]

I'd appreciate some help identifying the cause of an all-of-a-sudden problem with my Drake TR-7 (serial 66xx). The rig was, up until this morning, working fine...no issues. 

Now when I key the transmitter there is no measurable rf output (regardless of mode selected or setting of carrier control) and the digital display immediately counts upward to around 17+Mhz or 33Mhz depending on what band is selected. Un key the xmtr and receive is still fine. 

Front panel controls are set correctly. Using a dummy load instead of an antenna made no difference. I also noticed the meter backlight flickering when I try to insert a bit of carrier upon key-up. (???)

Before I take it out of the case and start looking, does anyone have a suggestion as to why it started doing this? I don't have a lot of digital experience. Still stuck in an analog/tube world, hi. Thanks a lot. Bill, w0ng