Mal
It's a long time since I owned Tulena my 22.
I did remove the keel and cleaned it up, best I could by hand, as its a 600lb lump of cast iron you can chip, hammer and grind at will to remove corrosion without risk of damage.
The keel lifting gear is easy to remove and dismantle, the only item that can wear out, apart from bearings is the brass block that travels along the stainless steel threaded rods. If the thread in the brass degrades too much it can strip completely allowing the keel to drop. I suspect a replacement would need to be fabricated. Obviously the wires should be replaced regularly.
Hopefully the bolts holding the green neoprene blocks have already been replaced with stainless steel, if you are unlucky enough to still have the steel bolts they will almost certainly require drilling out.
If you remove the keel check inside the box for wear from the neoprene blocks inside the box.
I hope this helps, I think there is more in the 22 manual.
Philip
superseal rascal