Really quirky electrical issues.

Can anybody tell me where the ignition fuse is located on this model and does anyone have a diagram of how to replace the ignition barrel?

The vehicle belongs to my father, and doesn't get used that much. Every so often, while driving along, the entire electrics die, but the engine continues to run. Pulling up and 'knocking' the ignition key seems to clear the problem. I can only imagine either the fusible link, the ignition fuse or the barrel is at fault, but if anybody has any other ideas, I'm open to alternative suggestions.

Thanks.