I've had two of these break on my Hayter Harrier 41 306R, so maybe the design is a little weak; however this is a minor niggle for a machine that has proved very durable and reliable. The first was replaced by my local garden machinery service centre, but the second I decided to do myself as it broke just before Easter. Replacement connecting rods are easy to obtain and I ordered mine from Mower Magic along with 4 Hayter Grip Fix (Starlock) washers; it was all very simple and delivery quick.
I had anticipated that the job would be a bit fiddly, but it turned out to be easier than expected.
Tools you will need:
a) A reasonably large sized cross head screwdriver;
b) Wire cutter or pliers;
c) A small ring spanner (say 10mm).
1) Start by removing the 2 height adjuster handle screws and ease off the handle along with the trigger and spring.
2) Prise off the 1 or 2 Starlock washers fixing the front part of the broken connecting rod to the front axle assembly and cut or twist it (them) off. Remove the rod and discard it along with the washer(s).
3) Follow the Hayter safety instructions for removing the cutterbar; i.e. drain the fuel and remove the spark plug lead before turning the mower onto its left hand side.
4) Rotate the rear roller down as far as possible to expose the rear part of the broken connecting rod and spring; if necessary remove the belt from the engine pulley after attaching some string to it to pull it back through the housing if necessary.
5) Remove the compensating spring then prise off and discard the Starlock washers from the rear end of the rod.
6) Insert the new rod through the housing so that it passes just inside the engine pulley. (I actually removed the rear roller assembly at this point but, in hindsight, it probably wasn't necessary (if it is, then a 1/4" socket set will be required to reach the axle support bolts). Push on a new Starlock washer to fix it to the rear roller frame, taking care to keep the washer straight; when lined up, the small ring spanner can then be used to push the washer home (a reasonable amount of force will be needed).
7) Reattach the compensating spring to the screw in the rear of the deck and bend in the connecting rod and carefully return the mower to the upright position. The weight of the mower will expand the spring and the connecting rod can then be linked to the front axle assembly which is rotated to line it up; attach a new Starlock washer as before.
8) Push the deck up and down and few times and visually inspect the area around the rear roller and belt to make sure that everything has been assembled correctly so that the belt is not rubbing etc.
9) I noticed that the previous repair had doubled up on the Starlock washers so, as this seemed a good idea, I did the same at this point (hence the need for 4 washers).
10) Replace the height adjuster handle along with trigger and spring; taking great care not to cross thread the screws into the deck.
I hope this helps...