Accessing boxed gutter in conservatory from underneath

[Zelfer]

We've recently had a number of what appear to be leaks from a box gutter in our conservatory that I'm trying to solve, So want to understand where it is actually coming from by looking underneath the guttering ( I recently had the gutter cleaned due to it overflowing due to blocked downpipe, wondering if this has had a side affect)
From outside :

The box gutter is boxed in from underneath as per the attached picture.
I can't push the bottom of the box up and pull it down, but that appears to be only bit not actually screwed or nailed in place. Is of a case of having to pull the side off, or am I being too gentle with the bottom, and try pulling it out using a suction cup type thing?

How would you go about accessing this area?


Thanks in advance.

 

[foxhole]

Access from below will be of little use, the gutter has to overflow to leak [blocked by leaf litter?] or end seals have failed.

 

[Zelfer]

Access from below will be of little use, the gutter has to overflow to leak [blocked by leaf litter?] or end seals have failed.

I'm wanting to see what's going on, hoping that access from underneath will allow me to see the source of the water, and therefore determine which of the 5 joints in the gutter run have failed.
However, after a huge downpour yesterday and today, there was no water running in, so not sure if it's a condensation problem on cold guttering, rather than a leak per say.

My biggest problem is in-ability to get to the top of the guttering easily - either standing on the roof, which I'm not sure will hold my weight, or lying on a conservatory roof, which again I'm not sure will hold my weight. Therefore I'm hoping that easier access from the bottom will minimise my need to work from above.