Abstract: A mechanism for use with a magnetic tape recorder having a tape drive composed of take-up and take-off reels, of buffer chambers allocated thereto, and a single tape capstan arranged between the buffer chambers and next to a write/read head. The tape capstan is reversible in the running direction. The mechanism of the present invention is for damping which opposes local deformations of the magnetic tape in the region of the head mirror of the magnetic head. This mechanism has a damping element in the form of a pneumatically acting jet comb comprising a plurality of nozzles residing under pressurization. These nozzles are arranged along a line proceeding transversely relative to the conveying direction of the magnetic tape and an air jet output by them impinges in the region of the leading ledge for the magnetic tape at the mirror of the magnetic head acting with a slight force component in tape conveying direction.