Hi, Kev,
Does your Corvette have a c220 setup? If it's u.k. production it will have. Going with that assumption, the small 'door interface' circuit board controls the accept/reject of each coin channel. The one I unpacked rejected all coins due to the switches on that board all being Off. AIR, working from the bottom upwards, the functions are; Channel 1, Chn. 2, Chn. 3, Chn.4 (they're certainly channels 1-4), then Chn. 7/8, Chn. 5/6 (again, these may be in the reverse order), 4 channel/8 channel, and Accept/Reject all coins. Channel refers to the acceptor, not necessarily the machines' coin inputs, D1-4.
Once the coins are registering (in the switch test D1 is usually '4th' (£1), D2 'Left' (50p), D3 'Centre' (20p) and D4 'Right' (10p)) you'll be able to set/check the pricing scheme.