Perhaps folk don't realize that this type of machine is not for playing 4 track tapes 2tracks in one direction and 2 in reverse?, this machine is meant for taping all 4 tracks in one direction but that can be done individually .
Years ago many musicians used these type of machines for producing demos of new music recording voice drum instruments on individual tracks and also using simul sync to mix even more music into the existing tracks.
Alan
Turntable - Garrard 401/Jelco 750L/Ortofon Kontrapunkt B, Pioneer PLC 590, Micro Sieki MA505 , Denon DL103R - DIY Paradise Phono stage - Reel 2 Reel Studer A810, Otari MX55,Tascam BR20, Revox A77, B77, PR99, TEAC X1000 & 3440, Digital HTPC / Young Dac - Preamp - DIY B4, 821, Power Amp's DIY Avondale NCC300 Mono Block, Speakers Wilmslow Kit Volt BM220.8 / Scanspeak D2905/9500