Sorry, no. The sentence is correct. 'Try' is the noun.
Correction!
No, white's d3-knight is being pressured, not the other way around. Try running through that part of the chess mentor, and you will see. It's not the grammar I'm pointing at, it's the physical pieces being referenced, duck_and_cover.
Sorry, no. The sentence is correct. 'Try' is the noun.
Play the mentor, yourself.

It's a very long paragraph and not obvious what the difference is. You may want to highlight it like this so people know what you're talking about:
"9...Ne5 is an interesting try to pressure Black's d3-knight. If White exchanges this knight, Black's dark-squared bishop would gain much in strength. Thus White should probably play 10.Nec1!? when White's defense looks good. Try for a similar execution of this idea."
It should say:
"9...Ne5 is an interesting try to pressure White's d3-knight. If White exchanges this knight, Black's dark-squared bishop would gain much in strength. Thus White should probably play 10.Nec1!? when White's defense looks good. Try for a similar execution of this idea."
Whoever is a mod and can edit the Chess Mentor text, there is an error in the Dynamic Compensation lesson where is says:
"9...Ne5 is an interesting try to pressure Black's d3-knight. If White exchanges this knight, Black's dark-squared bishop would gain much in strength. Thus White should probably play 10.Nec1!? when White's defense looks good. Try for a similar execution of this idea."
It should say:
"9...Ne5 is an interesting try to pressure White's d3-knight. If White exchanges this knight, Black's dark-squared bishop would gain much in strength. Thus White should probably play 10.Nec1!? when White's defense looks good. Try for a similar execution of this idea."
Glad I could be of help to the chess world!