I've used those adapters on a couple of watches (both Casios) and found the exact same problem with the replacement spring bars. Always worth using the originals.

Jays & Kays stuff is great. I bought the same adapters and also a Nato from them. I hate the 5610 with non black strap though. It just don't look right in anything apart from black. 1000% agree the Nato straps more comfortable than the Casio though.