"From time to time he does lift his knee. He's a driving player so it's something we're going to have to work with and we have been working with.
"We're just going to have to change that. There has been attention placed on it, and [we're] working with him practising at training and trying to eliminate it."
The Warriors firmly believe the incident was an accident but after considering Hurrell had twice been warned by the NRL to address his running technique, and factoring in the game's hardline stance against head knocks together with Tupou's extensive injuries, McFadden felt they faced an uphill battle to have the charge downgraded.
"The whole incident on the weekend we believe was an accident. There was nothing intentional in it," he said.
"There's a lot of scrutiny over head injuries so there's a lot of hype around it.
"We thought we had a good case but just in the context of the way the NRL is going at the moment we just thought we'd be doing very well to get it downgraded so we decided not to contest the charge."
Hurrell's suspension could not have come at a worse time for the Warriors. After struggling with a knee injury over the first month of football the 23-year-old returned for the round five match against Melbourne but battled to find his best form.
He paid the penalty for some sluggish displays when he was dropped to NSW Cup in round eight but bounced back with a good showing for Tonga against Samoa before making the ill-fated trip to Cronulla.
And while Hurrell's absence is a blow, McFadden is backing his replacement Dominique Peyroux to slot comfortably into their right-side attack.
"It's disappointing for him. He started to play some really good football on the weekend," McFadden said.
"But that's what you get dealt in this game. It is a challenge but I know Dom's done the job before and he's been in good form so there's no reason why he can't step in and do that job for us this week."
Getting Hurrell back in tip top shape is the next priority and the Warriors have some plans in place to make sure the 102kg ball-runner maintains his fitness during his stint on the sidelines.
"We're going to be a bit creative there. Obviously we need him to run. He has been carrying a knee injury so first and foremost it's a chance to let that settle down.
"We might get him doing some wrestling and some boxing. I know he enjoys that so it's important that he stays nice and motivated and comes back in very good condition."
Meanwhile, veteran winger Manu Vatuvei was recovering well from a sternum injury suffered against the Sharks with McFadden rating him a "50-50" chance of taking on the Eels at Parramatta on Saturday.
"After the game he was very sore and tender but he has responded very well to treatment.
"If you had have asked me after the match I would have said no chance but now he's probably more 50-50.
"We'll certainly take Manu over and just see how he feels but it's looking pretty positive."