Starting Over, Raiders Try to Forget ’90 Finish : Pro football: Six months after 51-3 battering by Buffalo, they open training camp at Oxnard.

Six months after that 51-3 mugging in Orchard Park, N.Y., the Raiders will rise again near the beaches of Oxnard, hoping to script a different ending to the 1991 season.

The Raiders, who open training camp for rookies today, with veterans due Friday, were 13-4 last season when a 48-point loss to the Buffalo Bills in the AFC championship game tainted an otherwise impressive return to prominence.

The Raiders spent the off-season vowing not to repeat the mistakes of history. To wit, they stole seven Super Bowl rings from the San Francisco 49ers, signing veteran safety Ronnie Lott and tailback Roger Craig as Plan B free agents.

Then, they bucked some conventional wisdom with the first-round selection of Todd Marinovich, who amassed many records as USC’s headstrong quarterback.

The Raiders also took a chance with a fourth-round choice on Raghib (Rocket) Ismail, the Notre Dame flash who opted for the Canadian Football League. Ah, but for how long?

Other training camp stories that bear watching:

--Jay Schroeder. The starting quarterback job is his to keep, despite his unraveling in a five-interception, AFC title-game performance. During the regular season, Schroeder established career-highs for completion percentage, 54.9; efficiency rating, 90.9, and touchdown-to-interception ratio, 19-9.

But what happens if Schroeder goes sour for a spell? Will the chants for Marinovich, ready or not, become deafening in the Coliseum? Good news for deep backup Steve Beuerlein, though. A new NFL rule allows a third, emergency quarterback to suit up each week, which should save Beuerlein some dry-cleaning bills.

Beuerlein, punished for his summer holdout in 1990, was not allowed in uniform all season.

--Running backs. The Raiders have too many. There are two Bells alone, Greg and second-round pick Nick, plus Marcus Allen, Craig, Vance Mueller, Steve Smith and Napoleon McCallum. That’s not counting the injured Bo Jackson, whose football career is presumed over by most medical experts.

If the veteran Craig can’t quickly regain the form of yesteryear, it could be a tough camp.

--Lott. The veteran hitter is making his third career position change, moving from free safety to strong safety, where he will be asked to shore up the soft Raider underbelly that was so badly exposed by the Bills’ no-huddle offense.

Raider Notes

The team hopes to have most, if not all, of its draft choices signed for the opening of camp. Even first-rounder Todd Marinovich and second-rounder Nick Bell? “We think we’ll get them done,” said Steve Ortmayer, director of football operations. As Sunday approached, the Raiders had signed sixth-round pick Nolan Harrison, a defensive tackle from Indiana, and were close on several other selections, Ortmayer said. . . . The Raiders need to sign at least one quarterback to conduct drills. All three veteran quarterbacks--Jay Schroeder, Vince Evans and Steve Beuerlein--were without contracts entering the weekend. The Raiders had 14 unsigned veterans overall, including the perennial late arrival, Marcus Allen.

January’s 48-point loss to Buffalo did not pass without its casualties. The Raiders made two defensive coaching changes in the aftermath, replacing line coach Bill Urbanik with former Raider assistant Earl Leggett and replacing linebackers coach Sam Gruneisen with Gunther Cunningham. . . . The Raiders will play a five-game exhibition season, starting July 27 at the Coliseum against the San Francisco 49ers.