Watson-Marlow 701S/R - Manual (Page 9)

Start the pump, allow any excess tubing to work through the pumphead, and
press the delivery end clamp down firmly. Check the tube for movement when
the pump is running.
Retensioning
the tubing
If there is any sign of the tube working its way through the pumphead, the
tube should be more firmly clamped at its suction end, the delivery end
unclamped to release any excess tubing, pulled tight and then firmly
reclamped again.
When using Marprene tubing, it is advised that the above procedure is
carried out after approximately 30 minutes running time following initial
tube loading. If the direction of flow is reversed, the tube should again
be checked for movement.
Page 9