In April, 1977, two Interstate Commerce Commission special agents made secret films of household goods movers in San Jose, Calif., loading bricks onto their trucks before weighing their moving loads and then charging the customers for the added weight.

"Those films of what is commonly known as "weight-bumping" - then overweighting of a load and resulting overcharging of the customer paying for the move - led the ICC in May, 1977, to open a major investigation into the extent of possible cheating in the household moving industry.

Yesterday, the ICC said that consumers are being bilked out of "tens of millions of dollers" by drivers, agents and moving companies breaking a wide variety of federal regulations aimed at protecting the consumer making a household move.

And the agency went to federal court in Chicago to charge one of the largest nationwide moving companies, National Van Lines, with nearly 3,000 violations in a seven month period last year.

Earlier this month, the ICC charged Mayflower Transit Co., the second largest national mover, with 21,698 similar violations.

But those two cases, the first fruits of the ICC probe led by investigations and Enforcement chief Peter Shannon, are said to be only "the tip of the iceberg."

According to Shannon, "our conclusion is that any truckers who want to bump weights can readily do so." He said that two ICC undercover agents who drove a truck through the Southeast were able to secure inflated weight tickets from officials working weight scales "about 70 percent of the time."

In the cases against National and Mayflower, the bulk of the alleged violations involved excessive delays in deliveries, overbooking and discriminatory practies. In the case of Mayflower, the ICC said, "one in four consumers utilizing Mayflower's services were inconvenienced by delays ranging from one to 147 days." The ICC has asked the courts to force the firms to follow federal regulations in the future.

But Shannon says that weightbumping may be even more extensive - and expensive. While a late delivery or pickup results in an average of $100 in added charges to the consumer for things like hotel accommodations or other inconveniences, weightbumping, on the average, costs the consumer $150-$200 a month, he said.

With an estimated 1.2 million interstate moves a year, Shannon estimates, and with an alleged 10 percent of those moves subjected to "bumps", that means that there are an estimated $20 million in overcharges in interstate moves alone. Shannon says 10 percents is an "extremely conservative" figure.

"And interstate moves are only about 10 to 20 percent of all moves," Shannon says. "Our information is that weightbumping is just as extensive on local moves, although the average dollar figures is probably less since the moves are generally less expensive."

"This is not a new problem," Shannon says. "But the industry has done little or nothing to stop it."

National Van Lines general counsel John P. Torpats disagreed, telling the Associated Press yesterday that he was "surprised by the suit since less than two weeks ago commission investigators said they were satisfied with the dramatic progress we have made in 1978." Torpats added that 1977 was a "horrendous year for the entire moving industry."

In its attempt to deal with the broad scope of the investigation, the ICC even used a team of 22 college students to highways in Florida, Arizona and Southern California between June 5 and July 17 of this year.

They found "5,960 significant violations of regulations aimed at protecting the consumer, (ranging from) bogus weight tickets on which transportation charges are based to fraudulently prepared manifest on which household good industry collect millions of dollars in accessorial charges," according to the ICC.

Shannon said some truckers have what they call "their own portable scales." They are stencils which can reproduce, "almost identically," certified weight tickets.

Charges against those involved in the student investigation will be lodged at the end of the summer, Shannon says.

While it would be extremely difficult to bring criminal charges against executives of the major corporations involved in household goods moving (nineteen movers handle 80 percent of all household goods shipments) ICC chairman Dan O'Neil said in a recent speech:

"These industry giants will not be immune if corporate involvement in weight bumping or any other pattern of consumer fraud can be established."