Thunderbird 900

Guys. Further to my thread about Thunderbird 900 , problem still present.
To recap bike runs great on open road, anything above 3000, rpm. Once into slow traffic or stopped as in traffic lights, it coughs and splutters, and invariably dies. 're starts no problem, but rough until revs up to 3000 ish. Carbs float chambers found to be full of crud and dirt so cleaned, jets cleaned, tank swilled out, and everything put back together. Overall, no change. ( it did run ok for a few miles but all back to square one ).I

Today I got tank off. There is still muck in tank so am swilling it out repeatedly to remove dirt, but, there appears to be something metal rolling about in tank. For the life of me, can't get it out. Any suggestions ?
Also, found a rubber hose from top of carbs but connected to nothing. There's a drain plug underneath the tank, towards rear, which I presume should be connected to that hose.
Suggestions appreciated.

 

Sprint Dave. Just to say managed to replace plugs and it near enough sorted the problem. Old plugs were finger tight and loose. But ......what a job getting to No.2. Someone in Triumph design needed their wrist slapped. Anyway, many thanks

 

Thanks Bikerman. I'll take that idea on board. A sod of a job for such a basic necessary undertaking.

 

Biker man..... Sorry thought I had replied. Managed to get the plugs sorted and found that the old ones were barely finger tight. Seriously there was movement before I tried to remove them. Bike now seems to be running almost the way it should. Still occasional hesitancy but almost sorted.
Wish I'd known about your trick then. Mind you, the space to get at them is ridiculously tight.I
Many many thanks for your help.