Pump Noise

I have a Hayward SP3400vsp 2.7hp Ecostar. 
purchased it about 7 years ago… about 1.5-2 years ago it was making a loud noise, so I brought it to a shop and they replaced the shaft seal, which fixed to noise problem.

my question is… its making a loud noise again… I’m not sure if it’s the same noise but… I purchased from you guys all the parts to replace to seal, o-rings gaskets etc.   how would I know if it’s actually the motor rather than the seal parts. Is there a way to distinguish between the 2 noises or will I just have to replace the seal, and if that doesn’t fix the noise, it’s probably the motor and I’ll need a new one?   Thanks in advance

Manny from NY