vw mk1 starter turns slow, drains battery too fast.

Ouch , this afternoon while
working on putting back pieces
of interior, the car refused to
start again, this was after I let it
run for about 30 min.
The issue now is that the starter
turns very slow or won't turn at
all. And it drains the battery with
jst abt 4 tries.
I even tried jump starting with
no luck, instead I could even
hear sound changing drastically
as if the other car is gonna stall.
What could be the problem now?

Have you tested the charging circuit ? Could also be a duff cell in the battery or an engine/battery earthing issue.

Thanks cero, I took off the starter, disassembled it, cleaned all parts with fuel then put it back,struggled to put brushes back in their positios but eventuall,  also cleaned the both leads. Cleaned the earthing positions and cabling. The starter have been operating like its new since then.