1. Place the bass in the left hand or pedals and supply the missing 3 upper parts.
2. Above the bass line you can see the numbers of intervals that should be calculated above the bass.
3. A sharp next to the number means that this note is sharpened.
4. A flat next to the number means that this note is flattened.
5. Make sure you avoid parallel fifths and octaves by moving the upper 3 parts in opposite direction than the bass.
Take a slow tempo, aim for a detached articulate legato touch and 3 correct repetitions in a row. Here's the MIDI file of the bass line (m. 25-32).
Post time and the number of repetitions to comments.