rb300 even if set to zero antiskate and perfectly leveled should swing slowly back to armlift. dial an antiskate first a-little less than the cartridge tracking weight.
if you have suspended turntable and detachable armboard than you should check level on the platter AND armboard as well.
if you have suspended turntable and detachable armboard than you should check level on the platter AND armboard as well.