As a lease-operator truck driver (1099), fixed costs can occasionally put a weekly settlement in debt. Where can I deduct repayments of negative balances?

I am an independent contractor (1099) leasing a commercial truck from my carrier. 
Repairs must be done through the company when possible, and can take a week or more. 

If the truck generates no revenue, certain fixed costs can bring weekly settlement payouts to $0. When the truck goes into debt, the debt accumulates as a 'Negative Balance Advance' which is repaid over time from future profitable settlements.

Where can I deduct this repayment amount?