McCoull will ride the Blacker-trained Cunning Fox in the second division of the Benchmark 64 Handicap and the four-year-old looks to have his hoof on the till.

However his style of racing is not ideally suited to the synthetic track and Blacker is hoping that will be offset by McCoull's skill and experience.

"The horse normally likes to get back in his races and, as we know, it can be hard to win from too far back at Spreyton," the trainer said.

"So I'm hoping Brendon might try to ride him a bit closer.

"I've kept him fresh, as he needs to be, and I'm sure he'll be hitting the line strongly."

Cunning Fox won his maiden over 1400m at Longford on New Year's Day and followed up with a 1600m Class 1 win at Mowbray a fortnight later.

The Foxwedge gelding resumed from a spell at the last Mowbray night meeting but drew barrier 1 which was an extreme disadvantage.

"I freshened him again after that race and took him to Spreyton a fortnight ago where he ran good sectionals and finished off strongly," Blacker said.

Cunning Fox, carrying a hefty 61kg, was checked at the start and settled last before making ground with the help of inside runs to finish third to Breathtaking and Braccenby.

"He will be better over further than 1350m so we might have to go up to a higher grade next start to find a 1650m race," Blacker said.

Bagdad harness trainer Paul Williams has been fined $3000 over a positive swab returned by his horse Chasing Cheetahs at Devonport three months ago.

A urine sample taken from Chasing Cheetahs, who finished fourth in the C2/C3 Pace on March 8, contained arsenic levels above the allowable threshold.

Williams pleaded guilty to presenting the horse to race when not free of all prohibited substances.

Stewards suspended half the fine on condition the trainer does not offend again in the next 12 months.

Meanwhile, an unnamed harness racing participant has been fined $1500 over an incident at the Mowbray race meeting on May 3.

The participant pleaded guilty to "acting in a manner detrimental to the industry" by deliberately causing damage to another participant's vehicle.

Half the fine was suspended on condition there is no further offending in the next 12 months.

Stewards refused to name the person involved as they said the incident was related to a on-going court case.