Document, document, document...
It would be a difficult thing to fire someone w/o any records of bad behavior, work issues, etc...not to mention the recourse they would have against the company w/o this information especially if they've been employed for a long amount of time. Sounds like it's time for some write-ups.
Is there a HR dept? Do these employees have files?
As far as improving attitude on the floor & getting these people to give a rats-azz, good luck...
Making people feel like they are part of a company & not only an employee, boosts the pride that they have in their positions rather than just showing up for work & clocking out at the end of the day.
Where I'm at, if that were applied things would be a wee bit different...the owner shows up, pretty much takes his ball & playground & bully's everyone. Yes, the bonus $$$ is great, but it still doesn't do a whole lot for attitudes when you don't feel like a part of the company.