WARNING: This page is about a different car, the 2002 Volvo C70, 2001 Volvo C70, 2000 Volvo C70, 1999 Volvo C70, and 1998 Volvo C70. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Carrier Plate
Courtesy of VOLVO CARS OF NORTH AMERICA.
Check that the carrier plate is not damaged or cracked.
Check that mating surfaces of the engine are clean. Check that the guide bushings for the transmission are intact and in position.