73 fork improvement

Hello all,
I was racing yesterday in vintage motocross with a BSA fitted with 1973 Husky forks and front wheel.
There seemed to be no damping effect on rebound with a harsh clunk at the end of the return travel.
Any tips to improve the action of these forks?
Cheers

Need some info to start with:

1) BSA weight with fuel and oil
2) Rider weight with helmet, boots, etc.
3) Are the fork legs aluminum (gray) or magnesium (black)?
4) How much do you want to spend?

Approaches in ascending order of cost:

1) Preload spacers
2) Oil weight and amount
3) Springs
4) Using 74/75 fork internals
5) Fork 'kits' - emulators or others

Start here for info / tech:

This link is for the aluminum (gray) legs - for the magnesium (black) legs, redo the search for a 74 250

https://racetech.com/ProductSearch/12/Husqvarna/250CR/1972

and:

https://racetech.com/page/id/140

Might also suggest a disassembly and inspection. I had simiar problems with the gray legs on my 400... when I tore them down I found one of the damping rods broken in two!

Thanks for your input.
Its the type with the grey unpainted fork legs that have the smaller diameter springs.
The race tech spring calculator stresses that the standard springs are way too soft for my weight! Not surprised there but my main concern is with the lack of rebound damping. Feels like there is none as the forks extend with a bang. This could snap the damper rod. I’ll be pulling the forks apart soon. From the link,I see that race tech sell piston bands for early husky forks. Not sure if these forks are meant to have them fitted.

No piston bands on grey legs... very simple fork design internally. The broken damper rod on mine was the cause of the lack of damping, especially noticeable on rebound. Not a common problem, but then we're dealing with parts that are 45 - 50 years old. Yes, original springs usually too soft. Haven't tried the Race Tech mods (yet). Here's a link to the 1973 Husqvarna parts list. Forks are in section B.
https://1drv.ms/b/s!Akhbhd3iqlMpgXwdItsgCsNquQ8Y

The topping out problem sounds like broken top out spring(s). If the forks sat in the weather for years rain most likely entered through the old seals. I've seen severley rusted top out springs more than once. I've never seen a broken dampening rod before like what SteveJ mentions. Damn, thats crazy to think of that occurring while riding.

I've researched Race Tech and all indications are the full RT mod, and I emphasize the word full, for the gray forks or black helps a lot. The cost for the full mod will run $500 and I can see where corners may be cut to save money but then end results suffer. With RT mod you end up with adjustable compression dampening allowing you to mechanically fine tune for weight, terrain, riding level. However rebound dampening adjustment is still limited to changes in the oil viscosity.