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Vintage Selmer Ampeg SVT Preamp Filtering Mod?

Hey all,

My old SVT started popping and cracking despite a fresh set of the power tubes recently so for the first time i went in to do some maintenance. I pretty easily recapped and replaced the power resistors in the power amp with a Fliptops kit. Upon entering the preamp section I noticed something unusual. There are a pair of 470mf 250v cans with clamps in the expected location of the 40-50mf cap. Can anyone guess why this would have been done? I'm planning to remove it all and just solder the 40mf cap to the side of the board. not sure if I'm in for any surprises. Amp sounded solid beforehand.
 

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The vintage style preamps tend to produce a bit of hum. My guess is the extra capacitance is probably an attempt to push the noise floor down a bit. I would be surprised if it worked as my understanding is the problem is cause by ground loops.