Join the Mannlicher Collectors Association. There's always ads in the back of their newsletter for replacement cleaning rods.

Others may weigh in. I have a similar rifle (including date of manufacture).

I hadn't fired it for years, but then the internet came along and made it far easier to find ammo.

I've had success on Gunbroker finding new old stock RWS ammo. I have also found RWS brass.

I did find one custom ammo maker who made some nice stuff, but used Hornady bullets. That in itself wasn't bad, but by crimping into the cannelure, the rounds were slightly short in overall length. Understand that these rifles can be very sensitive to length, and they had difficulty feeding (unlike the RWS rounds). There are other places that may make custom ammo, brass is available.

But the whole experience did lead to me learning how to hand load. Not only does this make me more comfortable with the future of using this rifle, it's cut down on the cost (and increased availability) for my pistol ammo.