"The Spy Who Loved Me," opening today at area theaters, gets off to a promising start but proves seriously deficient in staying power. Several diverting gambits put one in a receptive mood at the outlet: a KGB music box tinkles the theme from "Dr. Zhivago"; a stuntman doubling for Roger Moore as James Bond culminates a chase sequence filmed on Baffin Island with a stupendous, heart-stopping ski jump off a precipice and potentially into eternity; Maurice Binder contributes yet another splendidly suggestive credit sequence, topping even himself with silhouettes of women gymnasts swinging and vaulting from the barrel of Bond's Walther automatic.

It appears that the series may have recuperated promptly from the doldrums of the last Bond adventure, "The Man With the Golden Gun." Instead, Binder's credits turn out to be the high point of the show.

There's a splashy climactic battle sequence, staged across the majestic length and breadth of one of Ken Adam's cavernous sets, representing the interior of a supertanker concealing British, Soviet and American nuclear submarines hijacked by the villain, and it would probably match up with the equivalent showdowns in "You Only Live Twice" or "Thunderball" if contemplated in the abstract. Unfortunately, the interventing explosition has grown so stale and tedious that one can't take as much gratuitous pleasure in the spectacle of choreographed mayhem. In contrast to "Star Wars," for example, there's no suspense to be resolved in the climactic action of "The Spy Who Loved Me." One is simply grateful to see a ponderous vehicle nearing a conclusion.

While it never sags as alarmingly as its immediate predecessor, "Spy," the 10th film in the series, is at best a tolerable disappointment. The Bond movies have been so successful that it may be commercially impossible to terminate the series. However, it's been quite a while since a Bond adventure appeared to set fashions in escapist, glamorous entertainment. Once widely imitated and parodied by other producers, Bond films are now more likely to imitate themselves with decreasing effectiveness.

To cite one of the most glaring misjudgments, who cast Barbara Bach as the leading lady, a Russian spy whose hatred for Bond is supposed to evaporate as they work and play together? really does look indistinguishable from a Barbie doll. Pairing Bond with such a figure at this stage of the series can only make the hero and the filmmakers look ridiculous.

It might be hilariously appropriate to cast a model-starlet as waxen as Barbara Bach if one were planning the final put-down of Bond and wanted to make the point that a life-size Barbie doll was the logical extension of his desires. Coming from people presumably trying to sustain a popular formula, such a casting choice must be considered foolish or unconsciously revealing. Could it be producer Albert R. "Cubby" Broccoli or director Lewis Gilbert who has visions of Barbie dolls dancing around in his head?

The damage wouldn't be quite as acute if the script hadn't been contrived to emphasize an ongoing romantic relationship between Bond and his Soviet colleague, assigned to neutralize a power-mad villain impersonated without much gusto by Curt Jurgens. The movie requires some rapport between the leads to keep from floundering. As cartoon hero figures go. Roger Moore himself is rather too stylized and overrefined. Expecting sparks to fly between him and a plastic leading lady is asking for the impossible.

To his credit, Moore urged the producer to cast an actress in the role - Charlotte Rampling. According to Mrs. Moore, who accompanied her husband on a promotional swing through Washington yesterday, Broccoli disqualified Rampling on the grounds of insufficient bosom. As if there weren't enough overrendowed supernumerary starlets stationed on the perimeters of the movie already.

The big hulking menace, nicknamed "Jaws" and played by Richard Kiel, is deployed as ineffectively as the heroine. Perhaps Broccoli & Co. should refer to "Goldfinger" and notice how the character of Oddjob was kept just out of range until his climactic showdown with Bond. "Jaws" who could probably kill with his bare hands but with his steel-plated bridgework, keeps reappearing for one indecisive encounter after another with Bond. At the end he's even spared in order to return in the next installment, if needed. What the Bond series desperately needs is a firmer grip and fresher outlook at the upper echelon.