Some doubts

Hello.

I have a few questions, would be grateful for your help.

1. When I describe some past actions, which happened regularly during a certain period, I should use the past simple, not the past continuous, shouldn't I ? For example:

When we turned the key on the board all the contact came off. (I mean it happened regularly, not only once)

As the valve was broken, water filled the cellar. (regular event)

2. Is there a name for 'a dial with pointers' which is often used in machines? Can we say 'a pointer dial'?

3. In the kitchen, while looking at the power point, I noticed that some sparks were coming out of it.

Here it resembles a story, so I used the past continuous and past simple.

If I wanted to state simply that it happened regularly, could I only use the past simple?

I am describing a long list of technical problems in a house:

In the kitchen, when I looked at the power point from time to time, I noticed that sparks came out of it.

4. It happened for (a) certain time.

I think the article should be used here.

5. As there is not any explication on the board, we don't know what classroom go to.

6. The clock still does not work at the present time.

Is the usage of 'still' ok with the present simple?

I wanted to use a more complex word than 'now'...is 'at the present time' acceptable?

Thank you in advance.