QFX RETRO-39 Manuel D'instructions page 6

Maintenance
Your recorder requires no routine maintenance and under no circumstances should
you attempt to lubricate any parts of the machine.
However, parts of the machine, coming into direct contact with the tape, do require
periodic cleaning to ensure continuing good performance.
The tape heads (erase and record/play) may be cleaned using a cotton ball
moistened with a drop of isopropyl alcohol or proprietary tape head cleaner.
The pinch-roller and capstan shaft may be cleaned in a similar manner.
To gain proper access to these parts, remove any cassette from the compartment
and leave the lid raised. Pressing the Play key will engage the mechanics and move
all parts into view.
It will be easier to clean the entire surface of the pinch-roller if the power source is
connected (batteries or mains), so that the roller and capstan shaft rotate.
It is suggested that a proprietary Cassette Head Cleaning Cassette be used after
manually cleaning the Record/Play head in order to restore the polish and remove
surface film.
Pinch-Roller
Record/Play Head
Erase Head Capsian
PLAY
Failure to maintain the tape heads in clean condition will result in muffled
reproduction, poor recordings and incomplete erasure.
Failure to maintain the pinch-roller and capstan shaft in clean condition, is likely to
cause the tape to entangle and spill out of the cassette.
Do not touch the tape head with any metallic or sharp-pointed object.