In this guide
TL;DR: Leave the dryer off if the duct behind it has a sharp kink, flattened section, tear, or disconnected joint. Running another load to test it adds risk. The connector needs correction, along with the clearance that let it get crushed.
Inspect the transition duct from a safe side view
The transition duct carries warm, moist air and lint to the permanent exhaust. When the dryer is pushed too far back, it can flatten that connector, slow drying, increase heat, and encourage lint buildup. A coated screen, blocked outside hood, overloaded drum, or internal fault can also affect drying, but a visible crush needs correction first.
With the dryer off, use a flashlight or a phone camera on a stable handle from a safe side position. Stay off the appliance and clear of sharp metal. Unplug an electric dryer if you can reach the plug safely.
Leave a gas dryer in place for this check. Pulling a machine can strain a gas connector, rigid electrical conduit, stacked washer drain hose, or vent. If you smell gas, leave the area, avoid switches and flames, and follow the gas utility's emergency instructions.
Match the duct defect to its installation correction
A fold or flattened section
A qualified installer needs to restore the specified rear clearance and duct route. That may mean shortening an excess connector or choosing an approved low-profile fitting. If the alcove cannot hold the route without compression, change the layout. A new connector squeezed into the same space can be crushed again.
A tear, loose joint, or escaping lint
Replace and secure the connector by the specified method. Cloth and plastic tape are unsuitable hole patches. The dryer's manual governs material, diameter, maximum length, elbows, and fastening; apparent diameter alone is insufficient. Plastic or unidentified foil duct should be checked against current requirements by a qualified installer.
An intact approved connector
A smooth approved connector with a gentle curve needs its clearance maintained. Connections must not project into the airflow or form lint-catching edges, and the permanent exhaust needs support and a correct outdoor termination. Keep baskets, supplies, and other hoses out of the rear space.
Measure and mark the route before returning the dryer to position. Account for shelves, pedestals, and leveling adjustments that change the available room. If movement is necessary and safely authorized, grip the strong-frame points specified in the manual, with another adult watching the duct. Keep pressure off the door, controls, and top panel. A magnetic connection needs its own fit and material checks before installation.
Check airflow after duct shape and clearance are corrected
After the connector and clearance have been corrected, clean the lint screen and run a normal load under adult supervision. Watch the outside hood from ground level. Stop and get the exhaust assessed if you notice unusual heat, a hood that barely opens, a burning smell, or drying that remains unusually slow.
Inspect the route again from the safe side after several loads for a new fold. The U.S. Fire Administration's 2018 through 2020 home dryer-fire data identified failure to clean as the leading contributing ignition factor, so ongoing exhaust care remains necessary after the installation defect is corrected. For inaccessible lint or a difficult exhaust route, use the professional dryer-vent assessment guide.
Transition-duct questions
Will a vent brush fix a flattened connector?
No. The damaged connector and its clearance need correction before lint-cleaning work or an airflow test. A brush cannot restore the required duct shape or installation space.
Can I move a gas dryer to get a better view?
Leave it in place for this check. Use a safe side view and have qualified help manage access without straining its gas, electrical, or exhaust connections.