@Magnetron
I'm 100% certain that he knows how to 'band-aid' fix this problem, i.e. turn off automatic time in settings so that the device isn't getting Satellite time signals as "GPS" atomic time (presently UTC plus 18 seconds) which the device's internal algorithms then convert to local time as determined by it's satellite fix and in reference to it's loaded gmaptz.img map (he has the latest, V22). A manual adjustment of the local time by one hour 'fixes' it but that doesn't alter the fact that the device seems not to be accounting for daylight saving time in his location thus giving the one hour error. It's highly likely due to some minor but persistent corruption in the nonvol region 41. Erasing the region entirely will conclusively prove that's the problem if the time then shows correctly on 'automatic' however there is far more important information stored in rgn41 and it's not known how to remove only minor corruption from a dumped region 41 BIN file and then flash it back. However, it may be possible to force a deletion of non-essential non-volatile information (an action called "Clear Nonvol" and available only in devices later than his 10+ year old nuvi 255W) by doing a risky downgrade of firmware to a much lower version.

@SF
No luck yet finding the old versions. Have you tried erasing 41 yet? If it works i'll redouble my efforts to find them.