To measure what the consumption grade of the record and play heads of a Revox tape recorder is it usually needs a special reference tape and some electronic measuring devices.

The following should give you a first help before you decide if your recorder heads needs a check up before replacement or if you have to estimate a fair price of a used Revox tape recorder equipment. To look at the recorder heads will give you a rough estimate in what conditions this parts are without any electronic measurement. For concealed heads take a little mirror to spy.

The recorder heads are quite okay as long as visible wear of the play head and record head is below 1/8 inch. (approximately 3mm) Below that the recorder heads should be replaced to get the original recording and reproducing results.

Thanks to René for the information