Hi Bob,
The same issue with my TS-480 setup. It gets worse when my Internet connectivity is not perfect, but even when the Internet is just fine the CW is never perfect. As you said, if you send a long series of dots, you will hear the issue. The error may occur every 10, 20, or 30 seconds... but eventually the error does occur. Search this forum for various CW optimization settings, but I'm uncertain if error-free CW can be achieved. Has anyone achieved it?
73 Marvin VE3VEE