I had precisely the same problem on my late 745.
It is a relatively easy job to remove the scuttle panel (about 3 bolts across the inside lip once the bonnet is opened. Tip - don't remove the bonnet rubber seal as the scuttle draws upwards and off its side 'lock' pins with the seal attached.
I found the more difficult part was to extract the two wiper bosses from their drive spindles for which I bought a small puller off eBay rather than damage the paintwork.
I took some pics when I 'did' mine and can post them if wanted.
Bob
