Yet another 796 starting issue!

I've had my 796 for over 9 years now and it has always been a reluctant starter, requiring a bit of a roll back and forward to give it some encouragement.

Around 2years ago I upgraded to starter cables (Exact-start) and this seemed to help a little and then last year I decided to fit a new battery as I was still on the original.

I began having a problems around March time with the battery not charging and running on one cylinder. I managed to track this down to the connector block for the rectifier having come lose and melting its self on top of my horizontal cylinder.

Now I am thinking that I have a knackered battery, maybe as a result of the connector block issue. The bike will not turn over on the battery I just get a loud click/knock from the starter motor area. If I use my USB jump pack I can get it to start and once running my voltmeter will show 13.8 volts going into the battery.

My question now is will getting a lithium battery (higher cranking amps) solve my problem or do I have a starter motor issue? Is it needing more amps to turn it over? Do I need a new starter?

Anyone got any ideas?