Starting problem....

[Uberderv]

So, my starter needed changing because it had become 'lazy'. It would also just click when the key was turned and nowt would happen.
Anyway I bought a working one ( cheers Chris 90) fitted it and the car started..., starting instantly.
A day or two later the clicking noise is back but when it works it works great and starts within a crank or two.
Just looking for any suggestions on what to check.

Thanks in advance.