Yes 95% chance thats the area of problem.
The meter goes in series with the line. In other words
you are cutting one of the wires & inserting the meter.
Its a very common process so make up a little test jig.
If you happen to have a Sencore "Power Right" everything
is there for you, isolation, variac & metering. Great to have
but still costs $$ used due to its many uses.
73 Zeno
LFOD!