Former Liverpool striker Stan Collymore has urged Harry Kane to buck up his ideas if he wants to secure a big-money move away from Tottenham.Kane, 28, has yet to score in the Premier League this season after making four appearances. He has looked a shadow of the player that bagged 23 top-flight goals last term. The England skipper also led the line for the Three Lions at Euro 2020 and has notched nine international goals this year.The strikers future dominated the news over the summer, with Manchester City trying to take him to the Etihad. Kane was eager to move but the clubs could not agree on a price.Spurs chief Daniel Levy refused to budge over a reported £160m valuation. City offered less and also tried to include players in the deal but it was not to be.After returning late to pre-season, Kane made his season bow in the 1-0 Premier League victory over Wolves. He scored twice in a 3-1 Europa Conference League victory over Pacos de Ferreira.Top five punditry partnerships – Jimmy Greaves, Gary Neville, Jamie Carragher and moreAnd the prolific marksman was also on target in each of Englands three World Cup qualifiers earlier this month. But he has been way off the pace in the north Londoners recent league encounters.He was a virtual bystander as Chelsea took care of the hosts 3-0 at the Tottenham Hotspur Stadium on Sunday. Collymore believes that the Walthamstow-born aces heart is no longer in it with his present employers.And the ex-Aston Villa hitman feels he needs to prove to any possible suitor that he is not a spent force.Hes done at Tottenham, he wrote in his column for The Mirror. But if he thinks downing tools or being moody will get him a move to Manchester City – or any other club, for that matter – in January or next summer then hes very much mistaken.Clubs will pay the dough for a focused Kane but not a pale imitation of the goalscorer supreme who gets just 10 goals this season.So if he wants City to come again then he must stop moping and get about doing the business just as he always has done.City broke the British transfer record when signing Jack Grealish from Aston Villa in the off season. They paid the West Midlanders £100m for the England midfielder.He has begun life well at the Etihad, with City fifth in the standings after five games. However, they drew a blank against Southampton at the weekend and looked impotent up front.And Collymore has questioned whether the Grealish money could have been used to better effect elsewhere.By the looks of Citys goalless draw against Southampton on Saturday, they could do with an in-form Kane as well, he added. And Im starting to wonder if they spent their £100million on the wrong England superstar in the summer when they snapped up Jack Grealish.READ MORE: Tottenham suffer £50m blow to Nuno hopes of increasing firepower