Hey I am looking at the chat could you give me the number of the linkage? Is it number 3, 5 or 10?Ok, found a parts manual. Here is link.
Simplicity Broadmoor / 1600 / 2600 Manual (Page 24 of 65)
On page 24, I can see it is petal drive. The linkage from petal to trans looks like it has a slot in it. This would be adjustment.
Also looked and found manual I think?
Identification Numbers - Simplicity Broadmoor 2600 Series Operator's Manual [Page 4]
Page 28 shows adjusting brake, which may help too.