This video shows the repair of the bead (or ball) chain connection of the cruise control vacuum servo to the throttle cable and the installation of an aftermarket rubber boot done by a detail oriented hobbyist rather than a bang-it-out-as-fast-as-possible shop mechanic.
This servo is one of those parts that’s made of “unobtainium”, meaning it’s been discontinued for decades. Fortunately, the servo was ok; the problem was the end bead of the chain broke off. The original rubber boot that covers the bead chain had hardened and was as brittle as an eggshell. That boot was never offered as a stand-alone replacement part; it was included in the replacement servo assembly [GM Gr. 3.885, # 6494922]. A replacement boot was eventually offered beginning in 1981 [Gr. 3.885, # 25031301] but it’s slightly smaller in diameter on one end and the other end is lacking a flange. Nevertheless, identified as fitting 1984-1989 Corvettes, it’s the only boot that’s being reproduced. I used a reproduction boot in my repair.
By the way, an alternative servo that can be used is part # 6466530; although it's also made of unobtainium. The size of the bead chain is # 10 (3/16”) so you’ll need to use a #10 AD coupling and a small screw & nut to attach the chain to this alternate servo.
This isn’t what I would consider a “mission critical” repair, meaning, the engine won’t seize, axle won’t break, etc., if the cruise control isn’t fixed. However, I’m particular about having everything in my car function, including the bells & whistles. Besides, cruise control is nice to have.