Probably you're already aware, but just in case: If I understand correctly (not certain), the drum can be damaged (embrittled) if it got too hot, and also the spindle itself (though less likely).

Make sure the spindle is OK (shows no signs of overheating). Later models of the Alko axle allow replacement of the spindle but it sounds like yours does not? If there's spindle damage, just get a new axle assembly (including drums and brakes) from W&W.

Make sure the drums aren't damaged as well. If you're lucky, you can re-machine and paint the drums, replace the bearings, shoes and springs (kit available from W&W), and retain the axle and spindle.

NOTE: When corresponding with W&W regarding parts, send them a picture of the Alko part description which is on a plaque riveted to the bottom of the axle assembly (under the square tube running wheel-to-wheel).

Hope any of that is helpful!
Best Regards, Dave

PS: Please don't ask me why I know this...