Actually a new pump is only $50, why bother replacing a seal with the uncertainty it may not work properly.

The pump seal is the problem and it can lead to bearing damage if not caught soon enough. The seal used in the waterway pump is not as easy as most seals to replace. You are better off to have it done at a pump repair shop or pool store than to tackle it yourself unless you are familiar with this seal and have the tools to fix it. A repair bill would likely be under $75 for a seal replacement at a shop and they can replace the bearings if necessary.

John