The deferred tax liability at the end of year 3 will be $2,079 = ($780 + $780 + $519).
Pretax Income = $4,657( $7,192 − $2,535)
Taxable Income = $3,389[$7,192 − ($12,676 × 0.30)]
Deferred Tax liability for year 3 = $519[($4,657 − $3,389)(0.41)]

Deferred Tax liability for year 1 = $780[($4,657 − $2,755)(0.41)]
Deferred Tax liability for year 2 = $780[($4,657 − $2,755)(0.41)]

Alternative solution:
For tax purposes the machine is 100% depreciated out at the end of year three, while for GAAP it is only 60% depreciated.
The difference in depreciation is $12,676 × (1.00 − 0.60) = $5070.
Deferred tax liability = difference in depreciation × tax rate = $5070 × 0.41 = $2079.