Info needed: Help please: transmission problem

[Alastair Thomas]

The rebuild of our F60S progresses slowly but is threatening to come to a halt as a result of our latest problem.
On fitting the gear lever, we found that we could not select any gears.
We removed the shifter shaft housing and inspected it and it seems to work perfectly well on the bench i.e. all gear positions can be selected.
With the shifter shaft housing still removed, we satisfied ourselves that we could select gears by poking around by hand. It is true that the gears must be aligned, using the crank handle, for this to be possible.
Leaving the gears helpfully aligned, we refitted the shifter shaft housing to find that we could select reverse but still no forward gears (even the one we had helpfully aligned). We tried removing the gear lever and operating the selectors using a tyre lever but they would not budge.
This is a shortened version of a long and frustrating day. Has anyone any tips for this problem please.
Alastair
p.s. driving in reverse to Normandy next year promises to be a memorable experience.