I bought a used L2501 (100 hours) and when buying used I like to change oil and filters just to make sure these things are current in regards to calendar time and hours on the machine. I've changed the engine oil and filter, and the transmission filter plus various other checks. This all went very smoothly. I'm getting ready to change the hydraulic filter, but am a bit confused in regards to the magnet that is, I believe part of the filter, manual says to wipe off the magnet, but isn't a new magnet part of the new filter? If so, why would I need to wipe them from the old filter? Any guidance much appreciated.