Old man's ED starter not engaging

[donno]

There's a problem with the old man's ED. Whe the key is put to start, there's nothing, no clicks from the starter solenoid or relay, but the fuel pump is priming as it should. Its intermittent, and sometimes if you just hold it at start for a while, she'll spring into life. I initially was thinking key barrel, but it could also be a dud starter relay or inhibitor switch. Anyone else ever had this problem and know what's the go? Cheers for any help guys.

Donno