Property Damage Caused by Insured's Work

The claimant in this instance hired our insured to replace the metal cover on the top of a wheelchair lift and weld it into place. The old metal was thin and there was a patient that was larger than average, so the claimant wanted diamond-plated metal welded to the top of the lift. The claimant came after the work of the insured was finished and picked up the item. The next day, the claimant advised our insured that the lift did not work Our insured believes the welding work shorted out the electric harness and pump.

The claimant had the item repaired at another facility and had the entire lift replaced, and now seeks reimbursement from the insured. It is our opinion that exclusions j(6), k, and l on the CGL form apply so there is no coverage for the claim. What is your opinion?