Chas' Whim rebounded from an out-of-state drubbing to win the richest race on Laurel's program yesterday, and there was another four-legged force present.

Trainer King Leatherbury and jockey Mark Johnston combined to win three of the program's 10 live races, and fell a half-length short of a fourth when L'Enjobeau repelled Wild Kid in the finale. Their biggest purse was $16,800, a sum made more meaningful by the horse who brought it.

For weeks, Leatherbury had been trying to dispell speculation that Thirty Eight Go Go was a dwindling talent. The roan mare, actually more a light gray, had won only one race in 13 months, perplexing to Leatherbury because she had continued to train well.

Johnston believed Thirty Eight Go Go had lost her taste for turf, and with her shorter outing on dirt yesterday gave credence to the thought. With improved speed in the eighth race allowance sprint, she sat behind Queen's Reckoning in perfect striking position.

Johnston sat unflustered as Gregg McCarron hemmed them in astride Seraglio, simply waiting until Queen's Reckoning came off the rail in the stretch to push Thirty Eight Go Go past on the inside.

On a drying but muddy track, Thirty Eight Go Go covered 6 1/2 furlongs in 1:16 1/5, two-fifths of a second off the track record. The move suggested $1 million in earnings is within her reach after all; she's now past $825,000.

Leatherbury and Johnston won the two previous races with Study and Lace Of Love, both favorites.

The sun showed up by midafternoon, not in time to keep the $75,000 Japan Racing Association Handicap on the turf course. Trainer Rodger Gill had no problem with the consequent shift to the dirt track, for Chas' Whim had excelled on both surfaces.

He took the $45,000 winner's share by leading gate-to-wire, showing no ill effects from his poor showing in the Pennsylvania Derby three weeks back. Jockey Allen Stacy surmised the colt balked from dirt in his face that day and so eliminated the possibility.

Chas' Whim took the lead without much strain and proved too tough, even as Baltic Chill forged a gallant rally. He finished more than a length behind, Chas' Whim going the 1 1/8 miles in 1:49 3/5. Rosecroft Halts Contest

Rosecroft Raceway has postponed a $25,000 contest giveaway, a track spokesman said yesterday. The change of schedule came after owner Mark Vogel agreed to relinquish control of the harness track amid questions concerning his troubled real estate empire and the track's financial stability.

Originally scheduled for Oct. 5, the free contest would have required fans to pre-select a horse in each race to finish third or better -- in effect, a show parlay. Anyone who was correct in each race would have been assured of at least a share of the pot.