Pug Bipper injector question

[Fudgeybutter]

i have newly acquired a bipper "yay me" it smokes on start up, but once driven , goes , however comes back again when cold ( makes me think that an injector is leaking , Thus letting diesel build up in the exhaust system, ( showing white smoke until its burnt it off from the exhaust system )

i've taken the return feeds off ( i presume the nipples on top of the injectors are the return feed ) & have hooked up a leak test kit, so see if any diesel is able to go through the top of the injector into the block - this should hopefully tell me if one of them is staying open & dirt or built up in keeping it open

how hard are these injectors to get out ? im normally Petrol cars - so these are tad new to me.

do these injectors just pull out ? ( is the 2 nuts in between both sets of injectors holding them down ) ? - i dont want to go pulling random stuff.

thank you