After much shuffling to and fro through VADIS working out which gearbox may be fitted to your car I have found that code P0756 relates to Volvo code TCM-000C which is solenoid 2 hydraulic fault.
However, no matter which gearbox I have looked at it would appear that all the solenoids are in a control system box which is bolted to the outside of the gearbox.
This is probably what you did not wish to learn but if you can confirm the type of engine and gearbox I shall look further.
Work was good - retirement is better.
1996 850GLT 2.5 20v Estate Manual.
1995 Peugeot Boxer 2.5Tdi Autosleeper.
1984 244DL, Manual, Beige.
1987 744GLE, Manual, Green.
1991 960 3.0 24v, Auto, Silver.
1994 940T Wentworth, Auto, Blue.