1993 Marathon - brake spindle to axle spindle

[5J Farm]

Last year I replaced the rear brakes with new cable, new guts, and new drums. All was fine until yesterday (and it drove great all week). Tried to drive it and the motor ran, axles we’re turning, but wheels were not.
I took off the drums and unfortunately, the teeth inside are now quite smooth. Luckily the axle teeth seem to still have some bite left……but obviously not sure how much.
When I put them on last year, they were snug and I could feel the teeth grab and had to use a mallet to seat them.
Did I just happen to buy some serious cheap Chinese drums? Is this common? And is my axle shot?

[5J Farm]

Realized I titled this "brake spindle" and should be "brake drum spline". Oh well. Still perplexed if I should buy another one or plan on a new axle at the same time. I haven't take off the other drum.......but it appears to be gripping fine.