When Charles Anderson bought his two-bedroom condominium in Germantown three years ago, he thought he was making all the right moves.

As a first-time home buyer, he qualified to buy a county-subsidized Moderately Priced Dwelling Unit (MPDU) in Gunner's View, a garden condominium project built by Ryan Homes.

The price was right, and Anderson thought a condo would always be a snap to sell in the fast-growing I-270 corridor between Gaithersburg and Germantown.

But as it turns out, a host of unexpected factors, including the same government programs that helped him buy his unit a few years ago, are making it difficult for Anderson to unload it now.

"Probably a half dozen people have visited during open houses, but not one was in a position to buy," he said this week.

According to real estate brokers, dozens of others condo owners are facing the same problem because the Germantown market is being swamped by a glut of new condo construction.

At the same time, widespread publicity about area traffic congestion is causing potential buyers to look elsewhere, they said.

To make matters worse, big developers appear to have a strong competitive advantage over individual sellers in the softening market, despite a $5,000 to $10,000 difference in price between comparable new and used units.

The developers have been able to sell units steadily by participating in government-financed mortgage programs and by offering other incentives, such as mortgage rate buy-downs. As a result, individual sellers are the ones feeling the squeeze.

Anderson's 872-square-foot unit has been on the market for almost 10 months with hardly a nibble from a prospective purchaser, he said.

Yet, Ryan Homes has sold 65 garden condominiums in a new project a mile from his development, even though units that are essentially the same as his cost up to $6,000 more.

The difference: Most of the new Ryan homes were sold with the aid of 10.6 percent, fixed-rate mortgages that were financed through the sale of tax-exempt Montgomery County government bonds.

"It's a Catch 22. You're just going around in a vicious circle," said Michael E. Greenberg, a salesman with B & R Realty, which specializes in condominium and cooperative sales.

Since 1979, the county has financed about 4,000 low-interest home loans through tax-exempt bond sales. The overwhelming majority have been used to finance the purchase of new housing, said Joyce Siegel, a spokesman for the county's Housing Opportunities Commission.

The county is planning to issue its next round of low-interest mortgages in May, and Siegel said HOC officials are considering setting some aside for existing homes sales.

"There may be some money set aside. We're looking at whether to set aside for re-sell, but there's been no firm decision," she said.

In the six months between September and February, Ryan homes sold 49 condo units at its Knolls at North Lake development in Germantown through the HOC's low-interest financing program.

"Things have slowed down some since HOC, but we still have below-market financing," said Jay Henry, a Ryan salesman. "We have a buy-down that begins at 10 percent."

NVHomes of McLean sold out 248 units last December by also using a mixture of buy-downs and special financing, said Rus Walton, a production manager for the firm.

Anderson bought his condominium in 1982, because it was close to his job at the Bechtel Power Corp. on Shady Grove Road. Last year, he started working for a firm in Tysons Corner, which is in Fairfax.

The 25-mile commute, which took more than an hour each way, convinced him to move. He's now trying to sell his condo for $48,900, well below its appraised $51,000 market value.

"My main question is why are people primarily looking at new housing in the area and not used housing?" he said.

Greenberg, who is handling Anderson's property, said at least seven other condo owners in his development are in the same spot.

"It's beyond belief, really," he said. "People who live in the development are stuck. They just can't sell their property."