What are the hours of operation for customer service? Matt April 01, 2019 16:11 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 How do I reach customer service? Are there any authorized service technicians near me? How can I order parts for my machine? Where is the nearest Diamondback Fitness retail location or dealer (USA)? 510Ic Assembly Video Comments 0 comments Article is closed for comments.