Mod 1 for the KG-102A gyro capsule (P/N 060-0016-00) incorporates mechanical locking devices on the spin motor assembly and bearing end play adjustments. Quite simply, this modification should be incorporated when the gyro requires maintenance since service parts for gyros not containing this mod are no longer available.
The modification itself consists of installing a redesigned outer gimbals assembly and housing cap with a new bearing retainer and lock nut. The old style had glued in bearings.
The parts kit for installing this Mod is not cost prohibitive. However, due to the labor required to install the kit, the parts and labor cost exceed the gyro value in most cases.
Gyro capsules with serial numbers above 21390, KG-102A assemblies S/N 17698+, and KSG-105 assemblies S/N 3642+ should have had Mod 1 incorporated during original manufacturing. On such units, please note that Mod 1 is not marked on the dataplate(s).
In any case, to determine if a KG-102A gyro capsule has Mod 1 incorporated, inspect the gyro can mod chart either on top of the can (if available) or the gyro capsule dataplate underneath the can (3 screws must be removed). Please reference these pictures.