@Ted S - not in this case, but yes, I have had bad joiner connections happen as well: the joiner is just loose enough that there's no electrical contact, or there is electrical contact until there's just the right bump and it goes away (or comes back).
An alternative method to soldering I have used for joining 2 rails electrically (where the joiner is loose) is to drill a hole through each rail near the adjoining ends and running a small wire between them, secured with a micro pan head screw at each hole. 100% connectivity and zero problems.
