This thread, to me, represents the best of what newsgroups like this are
for.

1. The aforementioned "assume nothing". (probably should have been ALL CAPS)

2. Correlate stated or observed malfunction with:
a.) Visual inspection and yes, often smell checks.
b.) Power supply checks.
c.) Again, check for mechanically intermittent connections.

3. Don't assume too much from DC voltage checks with a multimeter. A 'scope
can often give you the best "eyes" into what the circuit is actually doing.

Nevertheless, a good multimeter can give really great information
interpreting voltage drops, finding leaky or shorted nodes, bias issues,
etc.

Too many people just start off re-capping for example, assuming this fixes
almost everything. I'm sick to death of hearing this from customers who have
been on the internet.

Another thread here, I see...

Mark Z.