I'm brand new to these forums so forgive me if I'm re-hashing an old subject. I've been using some Insteon products in my home now for probably more than 15 years. Over those years I've had several of the 2466 dimmer switches go bad on me and also one of the 2413S modems. In the past I just bit the bullet and bought new units to replace them when they went bad. However, now that I have a little more time on my hands I did some troubleshooting. The symptoms of my 2413S were: intermittent operation (sometimes it worked great, other times not at all), erratic indication of LED on the side of the unit. So I opened up the unit and started checking for the most likely culprit, bad electrolytic capacitors. In this case a small 10uF electrolytic capacitor was completely bad measuring 0uF. Replaced it and everything works great again. I found the same problem in the bad 2466 dimmers I took apart (2 of them). Replaced electrolytics and everything's good again. It seems Smarthome cut corners when sourcing parts for these and bought cheap junk.
Welcome to the forum. It's a well known problem reported on this forum and on the ISY forum. Bravo on your ability to troubleshoot and repair it. I repaired my PLM the same way and it's been working great for more than 10 years.
Known issue with 2413S,2413U and 2443 V2 Access Points (Built on a base 2413 main board). There is a very large thread on the UDI forums. On how we tested and replaced the filter capacitors in them. The 2413 uses a switching power supply and the capacitors where not rated to be in a switching power supply. The ones we replaced with where rated for switching supplies with a low ESR and long life. A few other Insteon modules have switching supplies and have issues also.
There should be no compatibility problems with the Icon line of switches. My ISY9941 with the latest 2413S PLM. Has no issues with the original hardware 2.0 Switchlinc Relays. That is the more featured version of the Icon line. My thoughts are the new 2477S that is Dual Band was receiving an RF signal due to a poor power line signal.
As mentioned. The original Insteon and Icon modules where power line only and used the I1 protocol for communications. Subject to power line noise and phase coupling issues. There is a greater amount of data flowing to and from the modules to the ISY994i. Lots of Peeks and Pokes to get one message sent. In the Event Viewer in Level3 you will see lots of activity to even just check a modules Link Database.
Besides being Dual Band the later modules also use I2 and I2CS protocols. So things like a message only take one Extended Insteon message to get things done.