1) Get a copy of the schematic / service manual: http://www.radiowrench.com/sonic/sil1011b2.pdf
You can find more Siltronix info here: http://www.cbtricks.com/radios/siltronix/index.htm
and more than you'll ever need to know here: http://www.radiowrench.com/siltronix/
2) RTFB, especially the sections on theory of operation and circuit descriptions. This may seem like a waste of time when you're anxious to get started, but at this stage of the game a pint of understanding can save you a gallon of troubleshooting time later. Working on the rig while you're clueless is the express lane to nowhere.
3) Power supply problems are relatively easy to track down. Typical circuit involves a fuse, switch, transformer, rectifier and AC ripple filter. Open up the chassis and give the smoky corner a good look. Like you mean it. With a flashlight. Both eyes open. Anything burnt? Fuse still good? Check the power switch with your ohmmeter across the switch contacts and from the switch to chassis ground. Unsolder or otherwise disconnect the transformer from the rectifier(s). Do the secondary windings still have continuity? Disconnect the rectifier(s) from the electrolytics and check them for conduction forward and reverse with the diode check function of your meter. If all OK so far, re-connect the transformer to the rectifier(s) but NOT
the filter electrolytics. Put some fire in the hole (and be prepared to kill power muy pronto
if the radio barks at you). AC volts coming off the transformer OK? Unfiltered DC volts coming off the rectifier(s) OK?Note: Confirm that your meter can handle the anticipated HV before measuring. Many meters are rated at 1,000 volts DC but only 600 volts AC.
4) If all OK you have what's probably the most common power supply failure... A shorted electrolytic. Next most likely failure is a shorted rectifier which can smoke a diode bridge - or - open a winding in the transformer secondary. You don't want to know what a replacement transformer costs.
5) You can test electrolytics (quick & dirty) with the 2k or diode check function of your meter. Measure the resistance across the condenser. Should start out very low then slowly rise to infinity. If it stays low it's shorted and needs to go. If it rises to infinity quickly it's only a fraction of the rated capacitance and needs to go.
6) If you find nothing wrong with the power supply it's time to move downstream in search of a partial short... Good Luck!
BTW: Considering the age of the radio it wouldn't hurt to rebuild the supply while you're in there. HV diodes typically used at the time were in the 750 to 1000 mil ballpark, today you can buy 1000 PIV 3 amp jobbies for pocket change and it's criminal not to upgrade them. And, speaking of criminal, you do know the Siltronix rigs were a favorite on the criminal band back when CW McCall still had a career... Don't be surprised if the rig has been modified by a Freeband Bubba.