FT-817 power plug

I found out what the problem was with the 4/1.7mm power plug I was using with my FT-817. The barrel of the plug (-ve) was not making contact with the solder terminal. I'd bought 3 of these plugs and the other 2 checked out OK with a meter. You can't see that the 2 parts aren't touching. I put a bit of solder between them.