Recently did an ASK-21 where the nylon tubing in the S-tubes of the pedals
was so old, it had hardened out and would not budge. At all. Whatsoever.
Applied heat by putting it in hot water, hairdrier an even a paint stripper
gun. Combined those with a custom built pull-device (cable broke!). Tried
cutting the diameter, knifetip broke. Sometimes everything you throw at it
does not work... Ended up welding new S-tubes to the pedals and putting new
guides in. Major work, to be done by a professional welder with the correct
authorization.