If the motor is the Electrolux version (black case grey end caps) on a 240

yes the magnet is likely the prblem. disassemble motor and reattach magnet to the case using metal epoxy. after repairing three wiper motors with similar prblms I learned the alternate style motor made by SKF is much better built, runs much more reliably and is quieter then the more common Electrolux motor. If you need a replacement, Id recommend getting an SKF motor from a 240 in the salvage yard

you'll be glad you did. SKF can be identified by the yellow band with

the word "Nahenstort" imprinted. Drop in swap only the firewall grommet

is different size make sure you get that grommet else you will find

water on the pass floor when it rains.

Mike