If wiggling the cable causes your pedal's power to cut out, it could be do to a damaged power jack, corrosion, or dirt on the power jack contacts.
First, verify that you are using a center negative, isolated 9V power supply that provides enough current for your pedal. The power plug should have 2.1mm inner diameter and 5.5mm outer diameter. That is a standard size for guitar pedals, but not for generic (non-pedal) AC adapters.
Next, check the power cable and plug to see if it is damaged, dirty, or corroded. The plug in the photo below is dented from constantly plugging and unplugging pedals on my desk, and no longer works reliably. Power cables can be frayed by rubbing against sharp edges of pedalboards or chewed by pets. If the plug or the cable are physically damaged, replace it with a new power cable. If it is dirty, clean it using isopropyl alcohol or a contact cleaner designed for audio plugs and jacks (CAIG DeoxIT Contact Cleaner is one example).
Corrosion, dust, and exposure to humid conditions can make the jack dirty. You can clean the power jack using a Gum Proxabrush go-between or similar interdental brush (a small brush that people wearing braces use to clean hard-to-reach parts of their teeth).
Turn off an unplug your pedal. Dip the brush in 70% or higher isopropyl alcohol. Tap the brush on the mouth of the bottle so that it is moist, but not dripping wet. Insert the brush into the power jack and clean the top side of the flat metal spring. Also clean the center pin. Move the brush in, out, and in circles. Repeat the process a few times with fresh isopropyl alcohol.
You can also clean the inside and outside of the power cable barrel connector (with power disconnected).
Wait at least an hour to let the power jack dry out, then reconnect power and see if the problem is improved.
The DC power jack has a cantilevered flat spring that contacts the outside of the barrel plug (positive voltage) and pushes the inside of the barrel against the pin (ground). The spring can be damaged if the power plug was stepped on or the pedal was dropped with a power cable connected. It is a standard DC power jack with 2.1mm inner diameter and 5.5mm outer diameter. Replacements are available through most electronics distributors or pedal building supply shops. One example is the Kobiconn 163-7620E-E (available from Mouser or Small Bear Electronics). Any music electronics technician should be able to replace it, but you can also contact us to perform the repair.