I have an old IC-745 I bought used last year. Recently it seems to be malfunctioning intermittently. It is receiving well on all bands as far as I can tell. Sometimes when transmitting, there is no RF power shown on the meter. I've tried the built in SWR meter when this happens, and there is no movement of the needle when I adjust the RF power with the meter in SET mode. My NanoVNA shows an SWR of < 1.1 on the frequencies I'm using (40m, 20m), so there doesn't seem to be any problem with the antenna.
The transceiver has seemed to work well (aside from being noisy, which is probably due to living in a city). I've received good signal reports since this began, but have only tried when the meter is working and showing a low SWR.
What's the best way to troubleshoot? I'm guessing the first step is to figure out whether the problem is actually low power or just a bad meter? I don't have an HF wattmeter, but have ordered one. I do have an oscilloscope and NanoVNA. Any suggestions on what this could be and how to troubleshoot?