UNLUCKY JAKE. His Harley Street doctor has no time for him because he's treating Sheikh Qarmat bin Ezzat el Sha'ket. "Someone from Asia" has grabbed his favorite spot on the double-decker bus. His psychiatrist's waiting room is cluttered with "folk from many lands and of nearly as many creeds." The queue at Paddington "would have served quite well as model for a Family of Man photograph," and "a citizen of Ghana" observes Jake's medicial treatment.

Nor is this influx of foreigners the only problem. His wife Brenda is fat and distant, her friend Alcestis drinks his rare French wine, the taxi rank near his house has been abandoned, his students are illiterate and scribble nasty graffiti in the library copies of his few scholarly articles, and there's a plan afoot to admit women to the Oxford college where he teaches.

But most of all, unlucky Jake because . . . well, let's just say that Jake's Thing refers to just what you think it does, and Jake's a bit worried about it. It's not that it won't - it's just that, now that he's past sixty, it doesn't really want to any more. The plot of this meandering comic novel centers on Jake's attempt to reviev what he calls his "libigh-do." He consults a psychiatrist, wears a "nocturnal mensurator" designed to measure his sexual impulses during sleep, performs half-clothed before a roomful of sex therapists, and commits a good deal of dutiful self-abuse (his chief fantasy-figure, intriguingly, is a skin-magazine model who resembles President Carter).

He also makes a carefully programmed effort to get things started again with Brenda, who seems quite interested in pepping up their sex life. The two spend a lot of time in "genital" and "non-genital sensate focusing sessions." And they go together to a series of group therapy sessions at which other people - not Jake, of course - scream and roll on the floor and cry quite a bit. Very unpleasant.

But none of it does much for Jake's - ah - problem, though others seem to respond smartly. Brenda, for example, slims down and livens up; their mutual friend Geoffrey, who begins coming to the group because he fears he doesn't exist, discovers that he does - so much so that he and Brenda run off together.

But Jake's main discovery comes, not on the couch or the martial bed, but in the common rooms of his Oxford college, where the ongoing debate on admission of women leads him to realize that he really doesn't like them very much at all:

"There will be women everywhere, chattering, gossiping, telling what they did today and what their daughter did yesterday and what their friend did last week and what somebody they heard about did last month and horrified if a chap brings up a topic or an argument. They don't mean what they say, they don't use language for discourse but for extending their personality, they take all disagreement ad opposition, yes, they do,even the brightest of them and that's the end of the search for truth, which is what the whole thing's supposed to be about."

So, feeling as he does, Jake has no difficulty making up his mind when the doctors discover that his problem may be due to a simple chemical imbalance which could be righted by taking pills. No, thanks, he says. Better off without all that.

As the foregoing may suggest, Jake's Thing is a fairly unpleasant ride, enlivened though it is with flashes of the fabled Amis wit. To his credit, Amis seems to realize that his main character is a thoroughly reprehensible, cold-fish type; but since we do not get to know the other characters well, one wonders why we are expected to enjoy so much of his company. The satire of British university life, of course, is strongly reminiscent of Amis' first novel, Lucky Jim . Incidents from the earlier novel reappera in Jake's Thing. and, in fact, Jake Richardson might easily be Jim Dixon himself, grown old and lazy, with a cushy academic job of the kind he used to cover and despice.

The years have not been kind to Jim-Jake. His one appealing quality was his willingness to endure any sort of madcap embarrassment and furor in the quest for his golden dream girl. Now, with declining "libigh-do", he's become a lazy pedant of the sort he once scorned. And, of course, the old Jim was willing to risk a fistfight to stick up for the postwar Labour government and the ordinary bloke's right to a share in the good things of British life. But Jake seems eager only for somebody to put the wogs in their place and make the taxis run properly again.

In the recent British election, art copied life: Amis, along with a number of former Labour intellectuals, endorsed the Conservative party. They won; now Jake has a government pledged to tighten up on immigration and go to the wall with the trade unions. One wonders if he'd be pleased though; they've allowed a woman into 10 Downing Street. Damn; another standard fallen. Unlucky Jake. Unlucky reader. CAPTION: Picture, Photo of Kingsley Amis by Mark Gerson