well I removed the window, I used a scalpel to break the paint n laquer seal around the rubber, and with not much pressure it popped inside the tank. however trying to get it out has proved impossible as the tank I did not realise is like a baffle in there that is the boxey bit of the tank, after an hr I gave in and left it in there.
now I wish I had gone the drilling route as it popped so easily.
new window fitted and tank back on bike and looks great. 1 more week and I can put polish on it

Yeah I wish I would have chimed in on never pushing it in on purpose. Though I think it was RT1 Pete that had good luck doing that? I pushed one in once by accident and shook the tank until it was back at the window hole and grabbed it with needle nose pliers and yanked it out. It’s probably just me but I would never leave an obstruction in the tank for fear of blocking off the oil flow. You won’t know until it seizes. Maybe the baffles will prevent that? Anyway ride at your own risk.

aye that did cross my mind, looking at the feed pipe, it has a half moon filter or sorts inside the tank so I assume its that shape in-case anything goes into the tank and blocks off flow, so I decided to button it up and fit the new window

Well, after yer sure the paint is fully cured... You'll be flipping it upside down and be able to grab the offending apparatus with long skinny nosed pliers? Tugging and cussing as it comes out the in port?
Sneezles61

Gary,
Can I ask where you ordered a new window from? I need one for my DT175.
Did you order part #360-21761-00-00 ?
Thanks

Hi
I got it from Yambits £15.00
it is under dt400b on his website

Thanks Gary.
I found it.