A multiplexer of a transmission section generates a clock signal by multiplying a reference clock signal of a digital image signal by a predetermined number \u2018K\u2019. The mounting block has an external surface formed to engage a complementary internal cavity of the wear tip and includes a pair of circumferentially-spaced sides oriented not more than 5 degrees from perpendicular to the cylindrical exterior surface of the wheel. In other preferred embodiments, a malleable section is located between the bendable tip and the shaft. If the request can be satisfied a notice of acceptance is sent and if it cannot, advice is given of this and a listing of alternate times is provided at which the request can be satisfied. by delaying the message for a fixed time.