Create an income type account in the chart of accounts called Gain/Loss on assets
then journal entries
debit gain/loss and credit the fixed asset account for the balance in the fixed asset account
deposit the check received and use the gain loss account as the source account for the deposit
debit the accumulated depreciation fixed asset account for the balance in that account and credit the gain loss account. If you have not declared and posted accumulated depreciation for the fixed asset, the IRS does not care on a year to year basis. BUT, they do care when the fixed asset is disposed of. If this is the case then you need to talk to a tax accountant about the entries needed.