It's unlikely that the vacuum pump is audible, and working. If it's drawing it's last breath, there's nothing you can do, it will fail harmlessly when it is done. If its high time, you might choose to change it preventatively, but it won't save you anything.
You could have one of several starter systems. The 150M is too recent to have a "pull clutch" unless the plane has been modified "backward", which is unlikely.
If it has a newer starter motor with an "injecting" pinion, have the starter checked/rebuilt. There are a number of sources of this service - no mystery there.
If it has a "key clutch", attend to it right away. A key clutch is the original configuration for that engine - it'll have a big Prestolite type starter motor bolted to a cast plate, bolted to the engine (also refer to the tech log for the engine). A person who is competent is to turn a propeller by hand, applying all the cautions appropriate should turn the propeller by its tip. If doing so enables the feel of the clutch engaging as the prop is turned backward, and releasing as it is turned forward, it's working as it should.
If the clutch does not release and engage (which can be a common fault) it's either not engaging, so the engine cannot be started, or it's not releasing = serious problem - do not run engine.!
Diagnose, and PM me if you like. If it's a starter clutch problem on the O-200, I have a lot of experience with these...
Let me know what you find...