Up for sale here is this brand new adapter circuit board. This will fit in the Marantz 1150 and 1150D, right where the old dual-section capacitor mounts. You can remove the old capacitor and clamp, and install this right in its place.

This is designed to hold two 35mm snap-in capacitors. You can use any capacitors that are 35mm in diameter and have a 10mm "pitch" (distance between terminals). This has holes that you can solder the old wires to, or you can use 3-position terminal blocks (not included). This is a fantastic solution to replace the old dual-section cap.

The original capacitor is two sections of 13000 uf 55v, so I would recommend replacing it with either two 12000 uf 63v caps or two 15000 uf 63v caps. A few good candidates at Mouser are:
ELH129M063AT5AA (12000 uf)
159LBB063M2EH (15000 uf)

US shipping and handling is $5, and international is $18, no matter what quantity you buy. All my small parts are set up for combined shipping, so you can just use the "add to cart" feature and then check out at once to get discounted shipping. If you have any questions, please ask.

Marantz 1150 1150D Capacitor Replacement Board Bare PCB to sub for Dual Cap