306.1 Repairs to Machines.

(a) When repairs to machines require only service or service with the use of an inconsequential amount of materials, the amount received is not subject to tax. (b) When material and service are used in making repairs to machines exempted under the machine exemption and when the materials used consist of standard replacement parts customarily used on such machines, neither service nor materials are subject to tax. (c) When material and service are used in repairing machines not exempted and when there is no separation in the billing, both materials and services are to be included in gross proceeds of sales. (d) When material and service are used in repairing taxable machines with service and materials shown separately, the material only is subject to the tax. (e) Materials are taxable in any event when sold to repairmen for use in making repairs where such materials lose their identity as a result of such use. For instance, paint, solder, lumber, and sheet metal.