The amplifier will work perfectly well with another brand of capacitor that has the same voltage rating and capacitance. I assume the cap you damaged is one of the Sprague silver cans. If the damaged cap is on the raised daughter board, it is close enough to the edge where you can get a soldering iron onto the leads from below and remove the cap. You can solder a new capacitor from the top to secure it and then heat from underneath to move it down to seat on the board, and then snip the leads. If the cap is the large 330uF silver can on the lower board and you can’t get to the pads from the top, the only way to get that replaced is by removing the board from the heat sink which means de-soldering all the output and driver transistors (that’s why it’s a $2,000 repair).
You will be hard pressed to find an equivalent amplifier because the 23,5 has excellent low impedance load driving. I would spend the budget in repairing the amplifier, but keep in mind it’s a 30 year-old beast that can have other issues (just like an old car with new tires). The biggest issue with this amp (and all other 30 year old high power amps) are the Rifa 4700pF EMF suppression capacitors -- which fail short when they age creating a fire hazard. Those are more critical to replace than power filter caps.