First, welcome to our Forum.........
The model 1450 was produced between 10/74 to 09/79. A chassis Serial Number would identify the month and year of production.
The "jerky action" of the hydro can be a number of things. I would start by examining the linkages from the Hydro Handle all the way back to the Hydro Unit itself and see if there is any slop and worn parts.
There is a lot of information in our Technical Library. You may want to look through it.
Parts are available from your local Cub Cadet Dealer and our Fine Sponsors listed in the boxes at the top of the page.