I recently replaced the stock ignition of my MLD28 with an RCEXL and at first was having all kinds of problems starting the engine. I tried 2 different 4.8 battery packs, bypassed the switch, etc. and nothing seemed to work. Then I tried a 6V pack and it seemed to work much better, but still I noticed the spark was intermittent. I know this ignition is supposed to work with 4.8 so I decided that maybe the module was bad and made arrangements to return it. Then I decided to try the RCEXL ignition with the original (MLD) hall sensor and guess what, it works with no issues. It may not happen too often, but hall sensors too can go bad or become intermittent.