"I could see something wasn't right with him so we gave him a break, missed some races and then tried to get him back," says Purdon.
"But he wasn't himself around the stables. He was still working well because he is a very good horse but he was sour with other horses.
"Then he went to Sydney and since he has come back he has been far more like his old self.
"He is in a better mood and working exceptionally so we are hopeful we can see something like is best this week."
Sky Major hinted at as much when he led and only narrowly went down in a dogfight with Smolda at Alexandra Park two weeks ago, his best performance this season.
But it is not Smolda, who has been in rampant form this year, with five wins including three group ones, that Purdon thinks is the horse to beat on Saturday.
"Smolda will be tough but I think Locharburn could be even tougher," says Purdon.
"We raced him quite a bit as a three-year-old and to be honest we could never beat him.
"He is a very good stayer and if he is spot on for Saturday night then he will be hard to beat."
Locharburn has returned to the track showing glimpses of his best this season, with a stunning national record for 2600m the most graphic reminder of his motor.
But he was disappointing in far weaker company last start and looked to be out of sorts in his action so will need to bounce back this Saturday.
Still, if he can work to the lead a sub 4:0 time for the 3200m looks certain.
Smolda is still the one to beat even from his 20m handicap, which may not be as bad as it sounds.
He is the only horse on a handicap and with the rest of the field off the front line, Smolda should simply attach on to the back of the bunch with no traffic concerns.
Winning from there still won't be easy but he came from a worse position after an early skip to push Arden Rooney to a head in the New Zealand Cup and his only two runs over 3200m since have produced an Auckland Cup third and a Hunter Cup win.
Smolda isn't the only serious group one player facing a back mark at Addington on Saturday, with Sheemon off a 40m handicap in the main trot in which Waterloo Sunset will be hard to beat for in-form trainer Paul Nairn.
Nairn also has Habibti Inta as favourite in the Trotting Stakes for two-year-olds while Delightful Memphis will be favoured to remain unbeaten in the juvenile fillies pace.
?With no Alexandra Park this week, the northern harness focus moves to Cambridge tonight and the traditional Hawera meeting.
The juvenile male pacers get some respite from taking on the Purdon-Rasmussen stars in tonight's Sires' Stakes heat and their absence points to Mongolian Hero (R5, No3) as the one to beat.
He was third to the All Stars pair of More The Better and Pacing Major in the two recent juvenile features at Alexandra Park and has the gate speed to use barrier three tonight.
Easter goodies
Best bet: Mongolian Hero (Cambridge tonight, R5): Was best of the rest behind All Stars babies recently. Tonight he races the rest.
Each way: Genociate (Hawera on Saturday, R3): Has some speed and the draw to use it.
Well-placed: Waterloo Sunset (Addington on Saturday, R11): Good trotter getting 20m start from Sheemon, which should be enough.
