noisy circulation pump

The circulation pump in my home is about 5 years old. It has been oiled on a regular basis and seems to have taken a liking to making sound now and then that would lead me to believe the bearings are shot. This consistent noise will occur for about two minutes then quit and become nice and quite for a half hour or so. While the noise is happening, I can lean on the motor and the noise will quit until I let up/off.

What's the diagnosis here? Do I need a new pump or should I mess with the bolts securing the pump to the water pipes?....