The team, which set up Leeds-based Hewlett Construction after the deal, were due to pay administrators BDO in a series of instalments.
Under the terms of the sale agreement the cash was due to be paid in full by the end of April, but according to a new report £621,000 is still outstanding.
According to administrators at BDO, the management team has struggled to renew contracts with some main contractors and faced challenges collecting the outstanding debts of the companies they acquired.
Rather than take punitive action, the accountants have extended the deadline to the end of October for the outstanding cash.
Managing director Alan Cooper and ex-chairman John Duffy, who is now a consultant to the firm, bought the three main Hewlett companies saving 300 jobs.
At the time they described the bank’s decision to call in administrators as a hostile move and a judgement which was premature and not backed by the directors.
According to the report failed Hewlett’s bank will receive significantly less than the £4.4m it is owed and trade creditors who submitted claims for £7.2m will not see a penny back.
Since the rescue deal Hewlett picked up a long term major job on the Priors Hall residential scheme on the eastern flank of Corby.
Hewlett is now contracted to be on site until 2015 carrying out earthworks, roads and drainage at the abandoned site to create a community of over 5,000 homes.
To help the project it plans to open its third regional office in the town.