This depends on several factors:

• Age of the dishwasher: If it's over 10 years old, replacement might be more cost-effective in the long run.
• Cost of repairs: If repairs are frequent and costly, investing in a new unit could save money on ongoing maintenance.
• Efficiency: Newer models are often more energy and water-efficient, which could lower operating costs. It’s advisable to get a quote from a technician and compare it to the cost of a new dishwasher.

Streaks can be caused by:

• Hard water deposits: A water softener or a rinse aid can help reduce streaks.
• Improper detergent use: Too much or too little detergent can leave residue. Use the recommended amount for commercial dishwashers.
• Dirty spray arms: If the spray arms are clogged, they may not rinse the dishes properly.
• Incorrect water temperature: The water should be at the manufacturer's recommended temperature, usually between 150°F and 160°F for washing.