KEF 105 maintenance

[kafu]

I am deciding whether to purchase a set of KEF 105s or the KEF 105.4 for critical listening purposes. I will be doing re-mastering work with these on music from the late 60s, and the 70s. I would appreciate anyone that has experience with these speakers to advise whether theses gems, after 2 decades of use, could have deteriorated in it's internal components that it no longer is fitted for this purposes. I am sure they sounded excellent when they were made 20 years ago. If they are still suitable, while certain maintenance is deemed necessary, what would you recommend i need changed.

Thank you for any advices.