KT17 starter-coil problems

[Roy Najecki]

About a month ago I loaned a family friend a few miles away my 682 with a KT17 Series I. He uses this every week to mow his lawn. A few days ago he calls and says it wouldn't start and he found the positive battery cable jacket had melted. That cable was replaced, terminals cleaned, battery charged, and still wouldn't start. So I drive over. The starter solenoid clicks and the engine barely starts to turn over or not at all. The battery is fully charged, and with a jumper battery connected.

Under the hood I notice the coil has apparently melted a bit with a strand of hardened black goo nearly reaching the engine block. Last year there were often times the starter wouldn't engage the engine so over the winter I replaced the original starter with one of those $60 starters on eBay. I presume for that price they are Chinese made. If the coil melting occurred last summer I can't recall.

With the engine cover off I checked the starter and find the starter cable post is loose yet the cable is tight to the post. So we disconnect the cable, tighten the nut underneath so now the post is tight to the starter, and reconnect the cable. We tried starting the engine and it does turn over, but very very slowly.

I don't know if this loose starter post has caused internal damage. Though I do assume it somehow caused increased electrical resistance and melting of the battery to solenoid cable jacket.

I've got a kit to rebuild my original starter which I presume will cause the engine to quickly turn over, even if the coil is bad and won't start the engine. I haven't yet done an electrical test of the coil. So is there anything else I should be looking at or doing?