Crew / machine repairer collusion

Collusion between a machine repairer and a ticket issuer is possible where specific ticket-issuing machines are allocated regularly to, or are retained by, the same individual. In such cases, the ticket issuer pays for tampering of the machine from the proceeds of the fraud that this enables.

To avoid or minimize such collusion, the random allocation of machines among all the crew is necessary. However there can be a benefit in the individual allocation, in that evidence of any tampering can be attributed to a specific ticket issuer.