Unusual to see only 5 year lifetime, likely it's just a cheap part- but electrolytic start capacitors have a bakelite case, large rubber bung+phenolic lid and do dry out, no "self-healing", they're not the greatest.
The same motor run capacitor is commonly used for many other 1/3HP door/furnace fan motors. It's a standard EIA case size (not metric).
Wayne Dalton/Challenger/Allstar 260572, 43-52 MFD 220-250VAC, 3.375" x 1.4375", 86x37mm.
Mallory/Cornell Dubilier PSU4335B
USD $17.75 MouserI would change over to a polypropylene film run cap, they don't dry out like electrolytics. But the physical size is bigger and many are 370-470VAC which is
huge, i.e. Kemet C276.It seems to be nominal 45uF +10/-5% to get the "43-52 MFD" range they give. But I saw a reference to same Westinghouse 1/3 HP motor 322P317 type 123C12 using 54uF 250VAC for the run cap. I wonder if 50uF would be better.
China’s national capacitor and resistor standard
GB/T 2470-1995 (GB2470-81) is used for their parts. They have completely taken over the motor capacitor business.
You had a type CD60 and changing to a CBB60 is what I would do, if it will fit. Their parts are metric.
CD60 Motor Start Capacitor, electrolytic, bakelite case (same as old part)
CBB60 Motor Run Capacitor, polypropylene. Will withstand 2X voltage surges.
CBB65 Motor Run Capacitor, polypropylene, oil-filled aluminum can, pressure safety switch. (these are huge)
Original part is 37x86mm, I see CBB60 45uF 250VAC are 40x70mm, 50uF is 45x90mm. 45uF 400VAC 50x106mm.
CBB65 45uF 370VAC oil-filled can is 50x110mm, 13mm or 1/2" bigger dia.