David Walker, 72, says he was horrified and "totally freaked out" when the scammer knocked on his door last week, telling Mr Walker his gutters needed cleaning.

It was the same man who allegedly violently attacked him last year, when Mr Walker refused to pay him twice for painting street numbers on his driveway.

"The problem is that a lot of these jobs, a few years ago I would've done myself but I can't do them anymore, 'cos I'm too old and too rocky on my feet," Mr Walker said.

"Guys like this tend to target old people. We can't do a lot of things that we used to, but because we're so used to doing themselves, we don't know where to go to get people to do them."

After the attack in April, Mr Walker had a security door installed. Police also put him in touch with northside community services.

"What I did was made a whole lot of contacts with people who could do work, so that if somebody turns up now and says, 'This job needs doing', there's somebody I can go to."

Mr Walker said he knows he is vulnerable to scammers. He has been repeatedly approached by people offering to complete odd jobs, but says these steps made him less of a target.

Mr Walker was unscathed after the latest encounter with the scammer – who apparently did not recognise the Ainslie man – and he hoped police caught up with him.

"The point about these guys is they are scammers, they don't do a good job," he said.

He asked if anyone saw a man matching the description – about 180cm tall, 50 to 60-years-old, caucasian, with short hair and a "stooping" walk – to please call the police.

Witnesses or inner north residents who believe they have seen the man can contact Crime Stoppers on 1800 333 000 or at act.crimestoppers.com.au.

with Megan Gorrey