Replace this:

{% if settings.show_slider_item_1 %}
		<!-- BEGIN .item -->
		<div class="item" style="background-image: url('{{ 'slider-item-1.jpg' | asset_url }}');">
			<div class="title-wrapper clearfix">
				<div class="title">
					{% assign title_size = settings.slider_item_1_title | size %}
					{% assign text_size = settings.slider_item_1_text | size %}
					{% if title_size > 0 %}
						<p class="clearfix"><a href="{{ settings.slider_item_1_link }}" class="headline">{{ settings.slider_item_1_title }}</a></p>
					{% endif %}
					{% if text_size > 0 %}
					<p class="clearfix"><a href="{{ settings.slider_item_1_link }}" class="intro">{{ settings.slider_item_1_text }} </a></p>
					{% endif %}
				</div>
			</div>
			<img src="{{ 'blank.png' | asset_url }}" alt="" />
		<!-- END .item -->
		</div>
		{% endif %}


with this (for all slider items):


{% if settings.show_slider_item_1 %}
		<!-- BEGIN .item -->
		<div class="item" style="background-image: url('{{ 'slider-item-1.jpg' | asset_url }}');">
			<img src="{{ 'blank.png' | asset_url }}" alt="" />
		<!-- END .item -->
		</div>
		{% endif %}