I agree 100%. I have a multi meter and all the tools.. I am very handy, although never worked on tube amp other than, disassembly, deoxit and tube swaps..Since no one else has chimed in here with words of warning: I still think you should buy a cheap multimeter to make sure your filter caps are drained and scrape that spot. While you have the "doghouse" under the chassis where the caps live open, look for signs of leakage. Take it in for servicing ASAP if you see any. Otherwise, just plan to get it serviced some time relatively soon, or learn how to do it yourself.
I honestly would like to learn to do most of the work myself (need to practice soldering on something cheap first) and learn how to drain the voltage before poking around the board..
To sum up, Id rather learn myself now and scrape the carbon before I drop $150 on a tech to do a couple hours worth of work.