Just six months ago West German Chancellor Helmut Schmidt clearly seemed to be the most dynamic political man of action in Western Europe.

The handsome articulate, 58-year-old West German leader probably still holds that dominant position today, but some of his image of leadership and outspokeness has faded noticeably in the past three months. Evento some of his party associates he seems uncharacteristically quiet, perhaps even a little depressed.

"We all think he'll bounce back," said one Social Democratic Party official, I would have to acknowledge that these last few months seem strange and a little disturbing.

Although Schmidt's left-center coalition of Social Democrats and Free Democrats was elected for another four-year term Oct. 3, the chancellor, by all accounts, has gotten off to a bad start this time around.

One Bonn newspaper, in an editorial sympathetic to Schmidt last week, portrayed him as almost an outsider within his own party an overstatement but nevertheless a reflectionof his odd, perhaps temporary, turnabout.

Questions over his leadership have prompted speculation about what would happen to the political landscape here if Schmidt ran into a prolonged decline. Some papers have asked whether former Chancellor Willy Brandt, still the chairman of the Social Democratic Party, could step in once again, or if a different alignment would emerge in a new government coalition.

Schmidt's problems go back to the October election, when his colition barely held onto office in the faceof heavy gains by combined conservative forces that reduced his once comfortable 46-seat majority in Parliament to 10 seats.

Still, everyone expected conversation gains, which, were it not for Schmidt's personal image of strong leadership, would have been even greater. That is why the apparent disappearance of strong leadership in the past few months is causing some unease in the ruling coalition.

On Dec. 15 in Parliament, Schmidt needed an absolute majority to confirm his coalition's victory at the polls. He got only one more vote than the minimum, a display that undoubutedly shook him.

This followed an uncharacteristic colossal political blunder when Schmidt tried to postpone old-age pension increases that his party had promised during the campaign. The proposal caused a furious outcry and Schmidt was forced not only to pull back but wound up delivering an unprecedented apology at the outset of his state-of'the-nation speech to Parliament.

That speech itself,which went on for 2 1/2 hours and was widely viewed as too long and dull, did much to contribute to the current idea that the former "Schmidt the Lip" may have lost some of his drive.

West Germany's generous pension system is, in fact, faced with deep deficits, but the political consequences of tampering with it so openly have been disastrous. The original idea to postpone the pension increases came during post-election negotiations between Schmidt's party and the small, conservative Free Democrats, without whose support Schmidt could not govern.

Those negotiations, in which the smaller party maneuvered for maximum clout within the coalition, reportedly were brutal and took an emotional toll on the chancellor.

The pension argument also forced the resignaion of Social Democrat Labor Minister Walter Arendt, one of the ablest members of Schmidt's Cabinet, raising further questions about the party's future leadership in any post-Schmidt era.

Speaking of Schmidt and recent events, one foreign diplomat here says, "It is interesting to see a man get beaten down like that. A year ago he was the most dynamic leader in the West. Now he knows votes will be tough to get in Parliament, and he probably only sees grief ahead. It could be Schmidt's winter of discontent."

A top leader of the Free Democrats feels, however, that Schmidt's current low profile is largely a reflection of the time between governments, partly a natural letdown after the rigors of a campaign and partly simply holiday time away from Bonn and politics. Schmidt returns here Monday after a two-week stay in Spain.

"The recent period was a bit boring," the Free Democrat leader said, "aside from the pension problem, which was a real mistake. But Schmidt is a man of action and he is at his best when things are active."