Having wrecked the stanchions on my Fox floats by not touching them for 6 years, I priced up the cost of a new CSU – it would have worked out at about £300 all-in for the new CSU and the service /work required to get someone to fit it all for me. Although I have serviced my forks in the past, fitting a new CSU might mean you need new bushings, plus I seem to be cack-handed and have wrecked Mrs NBT’s Rebas
I bit the bullet and paid £150 for some second hand Magura TS8s for my bike, then used the money saved to buy some brand new Rock Shox Sektors for Mrs NBT from rosebikes
Don’t get hung-up on “saving” money by replacing your CSU.