Physical size of capacitor too big......what now ???? Newbie...ish

I have a Monitor Audio Subwoofer - humming. The large capacitors need to be swapped - I hope (some bulge at top). Did a Mouser buy. They didn't really have a large selection. I ordered 2 and the size of capacitor is too large for both to sit side by side.
Any problem to mount one on underside of PCB board and other at its previous spot? If not, other options? My guess is adding some PCB board but you guys are the experts.
 
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