What are the hours of operation for customer service? Dan October 05, 2020 22:10 Updated Follow Daily Hours of Operation for Diamondback Fitness Customer Service: Monday-Friday 9am-5pm (MST) Closed Saturday/Sunday. Closed National and State Holidays. Related articles Where is the nearest Diamondback Fitness retail location or dealer (USA)? How can I order parts for my machine? Are there any authorized service technicians near me? 510Ic Assembly Video Comments 0 comments Article is closed for comments.