I'm hoping KO Staff can help me with this -

Yesterday I pulled my M03 Mini out of storage and tried to install a new ESC and radio gear into it. I attempted to bind my UR tx with the 901S module to my 408S rx, but even though I followed the instructions carefully, I could not get it to bind with the 408S.

I tried it with a 409S rx, and it worked perfectly (and the first time).

Is the UR compatible with the 408S ? On both occasions, the UR was in normal response mode. Both the 408S and 409S are brand new, and have never been "bound" with another tx. I also use the 408S with my Helios (with a 901S module) and have no problems.

The KO website says the 901S module should be compatible with the 408S receiver, but it doesn't specifically mention the UR....

BUMP

You would have to send the module and receiver in to be checked. There is nothing I can diagnose through a post if it works with another module.

Well I tried installing the offending 408S into another car with another ESC - no luck. I also tried binding it with my Helios (which has its own 901S module) - no success.

Looks like a dud receiver. Great.

Considering it's not under warranty, and with postage and repair costs to Japan, I'll probably just end up trashing it.

Just send it in. I blew up a 409 and it only cost around $20 to fix it. I'm not saying that yours will be that cheap but send it in.