I Have always preferred the hand control for hydros rather than the foot control.
The only thing that always seemed a bother on the HT20 was the foot control it worked well but always seemed overly sensitive to me. If I went over a rough spot in the yard it was almost impossible to hold it at a steady speed.
I was parting out a John Deere F510 last week and noticed that it had a damper cylinder on the hyro control.
Well the light bulb went off so I got out the drill 2 holes later and it was mounted on the HT.
Mowed with it today and it is so much nicer to control the speed that it is a joy to operate it now.
The sharp eyed Bolens guys will know what is not quite right with my idea ?? However it does work well.