Re: Bass Players
What style is your band, Tommy? Do you have any clips? Does he think of Chris Squire, Jack Bruce, John Entwhistle and Stanley Clarke as influences? Did he start with guitar and later moved to bass? Does he play with a pick rather than fingers? They'd all be telltale signs that Aydee's worked it out.
It's annoying when people take notice for a short while and relapse. From this side of the fence the answer is generally nagging. In HR (where I work) it's referred to as reinforcement.
Some people have very thick skulls with a very hard crust made up of pure ego ... these types usually require a fair bit of hammering to get messages across. Since he's a friend it might be worth going down the "reinforcement" road for a while rather than rushing to boot him out ... "I know you can do it because you've done it before" kind of encouragement.
If you've already nagged at him heaps, it might be worth asking him straight out if he'd prefer to change or to leave; he might not be interested unless he can play it is way.