It is worth checking battery and starter connections, and the ground strap from engine/trans to the body, just to make sure none of those are an issue, but most likely you need a new starter.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC