Two more cases of ATM skimming on Long Island were reported this week, including schemes at several grocery stores and a bank branch in August and September.

A skimmer was behind a series of unauthorized transactions on customer accounts at a Suffolk County National Bank location in Medford, according to the bank. Police also reported Thursday that men posing as repairmen were behind skimmers installed at automated teller machines inside five King Kullen locations in Nassau County.

So how can you avoid becoming a victim yourself?

Here is what law enforcement and the other government officials advise on protection:

Examine automated teller machines carefully

This photo, provided by Nassau County police, highlights the location of a skimming device on an ATM. Photo Credit: Nassau County police

Some card skimmers can be bulky, and they’re designed to only be in use for a few hours. Perpetrators can add an overlay onto the keypad to record personal identification numbers and also add a card reader attached to the card slot. Others get into the machine and put card-reading hardware on the inside.

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Nassau County police advise being suspicious of machine components that seem out of place. Check for tape, glue residue, pry marks and misaligned card slots. Suffolk County police advise tugging on the card slot hardware to make sure it’s attached to the machine.

Also check for hidden cameras, particularly those focused on the keypad. Cameras may be on a light fixture or attached as a bar to the top of the ATM machine.

Another sign something’s not right: There’s more resistance when you try to insert your card. That could be a sign of a “shimmer,” an internal device that records your card info, said Ian Kidman, of HTx Services, a Hauppauge-based ATM service company.

Be vigilant

This photo from Nassau County police shows the locations of skimming devices on an automated teller machine. Photo Credit: NCPD

The best ATMs to use are those inside, according to the FBI. Those are less likely to be tampered with, though not completely safe. High-traffic ATMs in tourist areas are particularly vulnerable.

The Office of the Comptroller of Currency also recommends watching for suspicious people near ATMs. Walk away if you feel someone is watching you, or a person offers to help you with the machine, especially machines that appear disabled.

The FBI notes that skimmers are not only found at ATMs, but also on gas pumps and credit card readers.

It helps to use your bank’s or another familiar ATM during business hours, Kidman said.

Criminals often know that unattended ATMs and those in convenience stores “aren’t protected with the latest and greatest fraud protction technology,” he said.

Even indoor bank ATMs that require you to swipe your card to get inside are vulnerable, he added. Use a card other than your debit card to get inside so criminals can’t sync up the data.

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Use common sense to protect information

One thing law enforcement organizations agree on: Check your bank statements and alert your bank to any suspicious activity. Act quickly if there are fraudulent charges. In some cases, federal law limits your liability, the amount you are responsible for, depending on how quickly you report the theft, according to the OCC.

“Banks are very understanding if they get a timely notification,” Kidman said. “If you call 30 or 60 days after the fact, they start asking questions and it may take longer to get reimbursed.”

Never write down your PIN number, and when typing in your PIN and other personal information into a machine, always cover the pad with your free hand to prevent bystanders from watching.

Kidman also recommends changing your PIN number once a month, but more frequently if you suspect you may have been a victim, or if card skimmers are being found in your area.

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It doesn’t hurt to set up alerts with your bank when large transactions are charged to your card either, he said.

Use your gut

If something doesn’t feel right, don’t hesitate to go somewhere else.