Philips N4511 tape recorder motionless

In my youth a Philips tape recorder was a possession that was both highly desired and practically unattainable. I was presented a few years ago with a Philips N4511 tape machine and would very much like to bring it back to life from its slumber.
Its general aspect is clean with no particular signs of much wear, especially inside. On switching it on, the right VU meter lights. The capstan motor turns and follows the speed change commands given by the corresponding slide switch. The two square-cut big belts inside look healthy. I checked the two fuses on the power supply unit: they are all right. The relay inside clicks when pushing the play, wind, rewind buttons, but these are the recorder’s only reactions. No other movement can be obtained, and neither the left VU meter nor any of the 6 push-buttons (rewind, wind, start, pause, record, stop) would light. I believe I shall be able to follow repair instructions given by your experts: I can use a soldering iron and a multimeter to some reasonable extent but not much beyond that.
I should be most grateful for help with bringing this tape recorder back to work.
Many anticipated thanks.