Starter draw on ignition

[Gold Digger]

I'm starting to notice on one of my A's that I sometimes have to let off my starter after whirling engine to get it to start. Have had this problem years ago but have forgot what I done to correct it. The starter was rebuilt completely about 6000 mile back and whirls good. Engine was tuned up about 1500 miles back. Battery is grounded to transmission with good connections. Seems like it just started occurring over night.