Cleaning the damper blades is always a good idea, they need to be able to slide in and out but not move forwards and backwards in their slots.
If you decide to replace with new (and why not, they are very cheap) note that you'll almost certainly need to trim them back a bit to shorten them, otherwise they'll foul on the vertical chassis member.
Many people favour replacing the damper blades with a more modern telescopic damper, but to be honest I have found the original blades to work very well indeed.
