Abstract: A primary seal for a normally operatively moveable shaft which may extend into fluid under pressure is adapted to be worked on without axially shifting the shaft, by secondarily sealing the shaft intermediate the primary seal and the fluid, thereby permitting working access to, removal and replacement of, the primary seal.Temporary support of the shaft while it remains in its operating position but separated from a primary supporting structure at one end is effected by activating selectively operable supporting means into supporting relation to an intermediate portion of the shaft, and from which the supporting means is inactivated when said one end is supported by the primary supporting structure.