i was wandering what i should get for the sealed units to open them up? i was thinking about going to walmart and getting a cheap angle grinder what kind of blades work the best for sealed units and how many can you cut through and does it cause sparks that can ignite the oil and go boom? im in the process of taking a sealed unit apart with a hacksaw so if you cut the top off it and leave the motor inside is it a unsealed unit lol im looking to spend no more than 25 dollars will it last? does brand name matter?